661285590 has 64 divisors (see below), whose sum is σ = 1821864960. Its totient is φ = 150480000.

The previous prime is 661285589. The next prime is 661285591. The reversal of 661285590 is 95582166.

It is an interprime number because it is at equal distance from previous prime (661285589) and next prime (661285591).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661285591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 41215 + ... + 54965.

It is an arithmetic number, because the mean of its divisors is an integer number (28466640).

Almost surely, 2^661285590 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661285590, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (910932480).

661285590 is an abundant number, since it is smaller than the sum of its proper divisors (1160579370).

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

661285590 is a wasteful number, since it uses less digits than its factorization.

661285590 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13997.

The product of its (nonzero) digits is 129600, while the sum is 42.

The square root of 661285590 is about 25715.4737463652. The cubic root of 661285590 is about 871.2237106516.

The spelling of 661285590 in words is "six hundred sixty-one million, two hundred eighty-five thousand, five hundred ninety".