509657661 has 6 divisors (see below), whose sum is σ = 736172190. Its totient is φ = 339771768.

The previous prime is 509657657. The next prime is 509657663. The reversal of 509657661 is 166756905.

It can be written as a sum of positive squares in only one way, i.e., 504900900 + 4756761 = 22470^2 + 2181^2 .

It is not a de Polignac number, because 509657661 - 2² = 509657657 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (509657663) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 28314306 + ... + 28314323.

It is an arithmetic number, because the mean of its divisors is an integer number (122695365).

Almost surely, 2^509657661 is an apocalyptic number.

It is an amenable number.

509657661 is a deficient number, since it is larger than the sum of its proper divisors (226514529).

509657661 is a wasteful number, since it uses less digits than its factorization.

509657661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56628635 (or 56628632 counting only the distinct ones).

The product of its (nonzero) digits is 340200, while the sum is 45.

The square root of 509657661 is about 22575.5987960453. The cubic root of 509657661 is about 798.7781666249.

The spelling of 509657661 in words is "five hundred nine million, six hundred fifty-seven thousand, six hundred sixty-one".