661550657 has 8 divisors (see below), whose sum is σ = 688411680. Its totient is φ = 635211360.

The previous prime is 661550653. The next prime is 661550671. The reversal of 661550657 is 756055166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 661550657 - 2² = 661550653 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661550651) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 127844 + ... + 132917.

It is an arithmetic number, because the mean of its divisors is an integer number (86051460).

Almost surely, 2^661550657 is an apocalyptic number.

It is an amenable number.

661550657 is a deficient number, since it is larger than the sum of its proper divisors (26861023).

661550657 is a wasteful number, since it uses less digits than its factorization.

661550657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 260863.

The product of its (nonzero) digits is 189000, while the sum is 41.

The square root of 661550657 is about 25720.6270724491. The cubic root of 661550657 is about 871.3401010132.

The spelling of 661550657 in words is "six hundred sixty-one million, five hundred fifty thousand, six hundred fifty-seven".