56721649 has 2 divisors, whose sum is σ = 56721650. Its totient is φ = 56721648.

The previous prime is 56721647. The next prime is 56721659. The reversal of 56721649 is 94612765.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55771024 + 950625 = 7468^2 + 975^2 .

It is a cyclic number.

It is not a de Polignac number, because 56721649 - 2¹ = 56721647 is a prime.

Together with 56721647, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (56721647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 28360824 + 28360825.

It is an arithmetic number, because the mean of its divisors is an integer number (28360825).

Almost surely, 2^56721649 is an apocalyptic number.

It is an amenable number.

56721649 is a deficient number, since it is larger than the sum of its proper divisors (1).

56721649 is an equidigital number, since it uses as much as digits as its factorization.

56721649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 90720, while the sum is 40.

The square root of 56721649 is about 7531.3776296239. The cubic root of 56721649 is about 384.2226379102. Note that the first 3 decimals are identical.

The spelling of 56721649 in words is "fifty-six million, seven hundred twenty-one thousand, six hundred forty-nine".