55811891 has 2 divisors, whose sum is σ = 55811892. Its totient is φ = 55811890.

The previous prime is 55811881. The next prime is 55811897. The reversal of 55811891 is 19811855.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55811891 is a prime.

It is a super-2 number, since 2×55811891² = 6229934353991762, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (55811897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27905945 + 27905946.

It is an arithmetic number, because the mean of its divisors is an integer number (27905946).

Almost surely, 2^55811891 is an apocalyptic number.

55811891 is a deficient number, since it is larger than the sum of its proper divisors (1).

55811891 is an equidigital number, since it uses as much as digits as its factorization.

55811891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14400, while the sum is 38.

The square root of 55811891 is about 7470.7356398149. The cubic root of 55811891 is about 382.1573755586.

The spelling of 55811891 in words is "fifty-five million, eight hundred eleven thousand, eight hundred ninety-one".