661051011665 has 32 divisors (see below), whose sum is σ = 880220027520. Its totient is φ = 472520896000.

The previous prime is 661051011653. The next prime is 661051011697. The reversal of 661051011665 is 566110150166.

It is not a de Polignac number, because 661051011665 - 2⁸ = 661051011409 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 18806687 + ... + 18841803.

It is an arithmetic number, because the mean of its divisors is an integer number (27506875860).

Almost surely, 2^661051011665 is an apocalyptic number.

It is an amenable number.

661051011665 is a deficient number, since it is larger than the sum of its proper divisors (219169015855).

661051011665 is a wasteful number, since it uses less digits than its factorization.

661051011665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40993.

The product of its (nonzero) digits is 32400, while the sum is 38.

The spelling of 661051011665 in words is "six hundred sixty-one billion, fifty-one million, eleven thousand, six hundred sixty-five".