661504016 has 10 divisors (see below), whose sum is σ = 1281664062. Its totient is φ = 330752000.

The previous prime is 661504003. The next prime is 661504021. The reversal of 661504016 is 610405166.

It can be written as a sum of positive squares in only one way, i.e., 387932416 + 273571600 = 19696^2 + 16540^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 661504016.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20671985 + ... + 20672016.

Almost surely, 2^661504016 is an apocalyptic number.

It is an amenable number.

661504016 is a deficient number, since it is larger than the sum of its proper divisors (620160046).

661504016 is a wasteful number, since it uses less digits than its factorization.

661504016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41344009 (or 41344003 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 661504016 is about 25719.7203717303. The cubic root of 661504016 is about 871.3196233026.

The spelling of 661504016 in words is "six hundred sixty-one million, five hundred four thousand, sixteen".