55815191 has 2 divisors, whose sum is σ = 55815192. Its totient is φ = 55815190.

The previous prime is 55815157. The next prime is 55815211. The reversal of 55815191 is 19151855.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 55815191 - 2⁶ = 55815127 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55815101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27907595 + 27907596.

It is an arithmetic number, because the mean of its divisors is an integer number (27907596).

Almost surely, 2^55815191 is an apocalyptic number.

55815191 is a deficient number, since it is larger than the sum of its proper divisors (1).

55815191 is an equidigital number, since it uses as much as digits as its factorization.

55815191 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9000, while the sum is 35.

The square root of 55815191 is about 7470.9564983341. The cubic root of 55815191 is about 382.1649073734.

The spelling of 55815191 in words is "fifty-five million, eight hundred fifteen thousand, one hundred ninety-one".