55651681 has 4 divisors (see below), whose sum is σ = 55711764. Its totient is φ = 55591600.

The previous prime is 55651679. The next prime is 55651699. The reversal of 55651681 is 18615655.

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

It can be written as a sum of positive squares in 2 ways, for example, as 34574400 + 21077281 = 5880^2 + 4591^2 .

It is a cyclic number.

It is not a de Polignac number, because 55651681 - 2¹ = 55651679 is a prime.

It is a super-2 number, since 2×55651681² = 6194219196251522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 55651681.

It is not an unprimeable number, because it can be changed into a prime (55651601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28630 + ... + 30511.

It is an arithmetic number, because the mean of its divisors is an integer number (13927941).

Almost surely, 2^55651681 is an apocalyptic number.

It is an amenable number.

55651681 is a deficient number, since it is larger than the sum of its proper divisors (60083).

55651681 is an equidigital number, since it uses as much as digits as its factorization.

55651681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60082.

The product of its digits is 36000, while the sum is 37.

The square root of 55651681 is about 7460.0054289524. The cubic root of 55651681 is about 381.7913597097.

It can be divided in two parts, 556516 and 81, that multiplied together give a square (45077796 = 6714²).

The spelling of 55651681 in words is "fifty-five million, six hundred fifty-one thousand, six hundred eighty-one".