661690944 has 168 divisors, whose sum is σ = 1986694528. Its totient is φ = 218350080.

The previous prime is 661690927. The next prime is 661690963. The reversal of 661690944 is 449096166.

It is a super-2 number, since 2×661690944² = 875669810743222272, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 661690944.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2441529 + ... + 2441799.

Almost surely, 2^661690944 is an apocalyptic number.

661690944 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661690944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (993347264).

661690944 is an abundant number, since it is smaller than the sum of its proper divisors (1325003584).

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

661690944 is a wasteful number, since it uses less digits than its factorization.

661690944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 455 (or 433 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 45.

The square root of 661690944 is about 25723.3540581317. The cubic root of 661690944 is about 871.4016881585.

The spelling of 661690944 in words is "six hundred sixty-one million, six hundred ninety thousand, nine hundred forty-four".