56721559 has 4 divisors (see below), whose sum is σ = 57154680. Its totient is φ = 56288440.

The previous prime is 56721557. The next prime is 56721563. The reversal of 56721559 is 95512765.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 56721559 - 2¹ = 56721557 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (56721551) 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 in 3 ways as a sum of consecutive naturals, for example, 216364 + ... + 216625.

It is an arithmetic number, because the mean of its divisors is an integer number (14288670).

Almost surely, 2^56721559 is an apocalyptic number.

56721559 is a deficient number, since it is larger than the sum of its proper divisors (433121).

56721559 is a wasteful number, since it uses less digits than its factorization.

56721559 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 433120.

The product of its digits is 94500, while the sum is 40.

The square root of 56721559 is about 7531.3716546191. The cubic root of 56721559 is about 384.2224346952. Note that the first 3 decimals are identical.

The spelling of 56721559 in words is "fifty-six million, seven hundred twenty-one thousand, five hundred fifty-nine".