656129813 has 4 divisors (see below), whose sum is σ = 658744128. Its totient is φ = 653515500.

The previous prime is 656129797. The next prime is 656129893. The reversal of 656129813 is 318921656.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 656129813 - 2⁴ = 656129797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656129893) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1306781 + ... + 1307282.

It is an arithmetic number, because the mean of its divisors is an integer number (164686032).

Almost surely, 2^656129813 is an apocalyptic number.

It is an amenable number.

656129813 is a deficient number, since it is larger than the sum of its proper divisors (2614315).

656129813 is a wasteful number, since it uses less digits than its factorization.

656129813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2614314.

The product of its digits is 77760, while the sum is 41.

The square root of 656129813 is about 25615.0309974437. The cubic root of 656129813 is about 868.9536074158.

The spelling of 656129813 in words is "six hundred fifty-six million, one hundred twenty-nine thousand, eight hundred thirteen".