661358790 has 128 divisors (see below), whose sum is σ = 1851724800. Its totient is φ = 167650560.

The previous prime is 661358729. The next prime is 661358851. The reversal of 661358790 is 97853166.

It is a happy number.

661358790 is a `hidden beast` number, since 6 + 61 + 3 + 587 + 9 + 0 = 666.

661358790 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (661358729) and next prime (661358851).

It is a super-2 number, since 2×661358790² = 874790898220528200, which contains 22 as substring.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1744821 + ... + 1745199.

It is an arithmetic number, because the mean of its divisors is an integer number (14466600).

Almost surely, 2^661358790 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661358790, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (925862400).

661358790 is an abundant number, since it is smaller than the sum of its proper divisors (1190366010).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661358790 is a wasteful number, since it uses less digits than its factorization.

661358790 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 699 (or 693 counting only the distinct ones).

The product of its (nonzero) digits is 272160, while the sum is 45.

The square root of 661358790 is about 25716.8969745574. The cubic root of 661358790 is about 871.2558557256.

The spelling of 661358790 in words is "six hundred sixty-one million, three hundred fifty-eight thousand, seven hundred ninety".