661022920 has 64 divisors (see below), whose sum is σ = 1616140800. Its totient is φ = 242403840.

The previous prime is 661022911. The next prime is 661022953. The reversal of 661022920 is 29220166.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9532 + ... + 37588.

It is an arithmetic number, because the mean of its divisors is an integer number (25252200).

Almost surely, 2^661022920 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661022920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (808070400).

661022920 is an abundant number, since it is smaller than the sum of its proper divisors (955117880).

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

661022920 is a wasteful number, since it uses less digits than its factorization.

661022920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28118 (or 28114 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 661022920 is about 25710.3660028402. The cubic root of 661022920 is about 871.1083421220.

The spelling of 661022920 in words is "six hundred sixty-one million, twenty-two thousand, nine hundred twenty".