55681991 has 8 divisors (see below), whose sum is σ = 56743200. Its totient is φ = 54628992.

The previous prime is 55681973. The next prime is 55682009. The reversal of 55681991 is 19918655.

It is an interprime number because it is at equal distance from previous prime (55681973) and next prime (55682009).

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 55681991 - 2²² = 51487687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55681391) 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, 12611 + ... + 16443.

It is an arithmetic number, because the mean of its divisors is an integer number (7092900).

Almost surely, 2^55681991 is an apocalyptic number.

55681991 is a deficient number, since it is larger than the sum of its proper divisors (1061209).

55681991 is a wasteful number, since it uses less digits than its factorization.

55681991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4105.

The product of its digits is 97200, while the sum is 44.

The square root of 55681991 is about 7462.0366522820. The cubic root of 55681991 is about 381.8606597780.

The spelling of 55681991 in words is "fifty-five million, six hundred eighty-one thousand, nine hundred ninety-one".