661766490 has 256 divisors, whose sum is σ = 2225664000. Its totient is φ = 135924480.

The previous prime is 661766473. The next prime is 661766503. The reversal of 661766490 is 94667166.

It is a happy number.

661766490 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 2889696 + ... + 2889924.

It is an arithmetic number, because the mean of its divisors is an integer number (8694000).

Almost surely, 2^661766490 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661766490, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1112832000).

661766490 is an abundant number, since it is smaller than the sum of its proper divisors (1563897510).

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

661766490 is a wasteful number, since it uses less digits than its factorization.

661766490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 402 (or 396 counting only the distinct ones).

The product of its (nonzero) digits is 326592, while the sum is 45.

The square root of 661766490 is about 25724.8224483669. The cubic root of 661766490 is about 871.4348498671.

The spelling of 661766490 in words is "six hundred sixty-one million, seven hundred sixty-six thousand, four hundred ninety".