661777138 has 32 divisors (see below), whose sum is σ = 1113108480. Its totient is φ = 292482960.

The previous prime is 661777111. The next prime is 661777147. The reversal of 661777138 is 831777166.

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, 224631 + ... + 227557.

It is an arithmetic number, because the mean of its divisors is an integer number (34784640).

Almost surely, 2^661777138 is an apocalyptic number.

661777138 is a deficient number, since it is larger than the sum of its proper divisors (451331342).

661777138 is a wasteful number, since it uses less digits than its factorization.

661777138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3222.

The product of its digits is 296352, while the sum is 46.

The square root of 661777138 is about 25725.0294071746. The cubic root of 661777138 is about 871.4395237154.

The spelling of 661777138 in words is "six hundred sixty-one million, seven hundred seventy-seven thousand, one hundred thirty-eight".