55721581 has 8 divisors (see below), whose sum is σ = 56640384. Its totient is φ = 54806640.

The previous prime is 55721579. The next prime is 55721629. The reversal of 55721581 is 18512755.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 55721581 - 2¹ = 55721579 is a prime.

It is a super-2 number, since 2×55721581² = 6209789178279122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55721551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45331 + ... + 46543.

It is an arithmetic number, because the mean of its divisors is an integer number (7080048).

Almost surely, 2^55721581 is an apocalyptic number.

It is an amenable number.

55721581 is a deficient number, since it is larger than the sum of its proper divisors (918803).

55721581 is a wasteful number, since it uses less digits than its factorization.

55721581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1931.

The product of its digits is 14000, while the sum is 34.

The square root of 55721581 is about 7464.6889419453. The cubic root of 55721581 is about 381.9511395526.

The spelling of 55721581 in words is "fifty-five million, seven hundred twenty-one thousand, five hundred eighty-one".