721656131 has 16 divisors (see below), whose sum is σ = 833034240. Its totient is φ = 612375360.

The previous prime is 721656127. The next prime is 721656149. The reversal of 721656131 is 131656127.

It is a cyclic number.

It is not a de Polignac number, because 721656131 - 2² = 721656127 is a prime.

It is a super-2 number, since 2×721656131² = 1041575142819778322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721656121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 458576 + ... + 460146.

It is an arithmetic number, because the mean of its divisors is an integer number (52064640).

Almost surely, 2^721656131 is an apocalyptic number.

721656131 is a deficient number, since it is larger than the sum of its proper divisors (111378109).

721656131 is a wasteful number, since it uses less digits than its factorization.

721656131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2194.

The product of its digits is 7560, while the sum is 32.

The square root of 721656131 is about 26863.6581835014. The cubic root of 721656131 is about 896.9676261719.

The spelling of 721656131 in words is "seven hundred twenty-one million, six hundred fifty-six thousand, one hundred thirty-one".