55621681 has 8 divisors (see below), whose sum is σ = 57657600. Its totient is φ = 53593680.

The previous prime is 55621679. The next prime is 55621697. The reversal of 55621681 is 18612655.

It is a happy number.

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 55621681 - 2¹ = 55621679 is a prime.

It is a super-2 number, since 2×55621681² = 6187542794531522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55621381) 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 7 ways as a sum of consecutive naturals, for example, 14880 + ... + 18238.

It is an arithmetic number, because the mean of its divisors is an integer number (7207200).

Almost surely, 2^55621681 is an apocalyptic number.

It is an amenable number.

55621681 is a deficient number, since it is larger than the sum of its proper divisors (2035919).

55621681 is a wasteful number, since it uses less digits than its factorization.

55621681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3959.

The product of its digits is 14400, while the sum is 34.

The square root of 55621681 is about 7457.9944355034. The cubic root of 55621681 is about 381.7227436361.

The spelling of 55621681 in words is "fifty-five million, six hundred twenty-one thousand, six hundred eighty-one".