661970644 has 24 divisors (see below), whose sum is σ = 1168813800. Its totient is φ = 328034304.

The previous prime is 661970627. The next prime is 661970651. The reversal of 661970644 is 446079166.

It can be written as a sum of positive squares in 4 ways, for example, as 4048144 + 657922500 = 2012^2 + 25650^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 661970644.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 352492 + ... + 354364.

It is an arithmetic number, because the mean of its divisors is an integer number (48700575).

Almost surely, 2^661970644 is an apocalyptic number.

It is an amenable number.

661970644 is a deficient number, since it is larger than the sum of its proper divisors (506843156).

661970644 is a wasteful number, since it uses less digits than its factorization.

661970644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2619 (or 2617 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 43.

The square root of 661970644 is about 25728.7901775424. The cubic root of 661970644 is about 871.5244527817.

The spelling of 661970644 in words is "six hundred sixty-one million, nine hundred seventy thousand, six hundred forty-four".