55815491 has 2 divisors, whose sum is σ = 55815492. Its totient is φ = 55815490.

The previous prime is 55815479. The next prime is 55815493. The reversal of 55815491 is 19451855.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 55815491 - 2¹⁰ = 55814467 is a prime.

Together with 55815493, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_3327986 and since 55815491 and 3327986 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (55815493) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27907745 + 27907746.

It is an arithmetic number, because the mean of its divisors is an integer number (27907746).

Almost surely, 2^55815491 is an apocalyptic number.

55815491 is a deficient number, since it is larger than the sum of its proper divisors (1).

55815491 is an equidigital number, since it uses as much as digits as its factorization.

55815491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36000, while the sum is 38.

The square root of 55815491 is about 7470.9765760575. The cubic root of 55815491 is about 382.1655920692.

The spelling of 55815491 in words is "fifty-five million, eight hundred fifteen thousand, four hundred ninety-one".