55640891 has 2 divisors, whose sum is σ = 55640892. Its totient is φ = 55640890.

The previous prime is 55640869. The next prime is 55640899. The reversal of 55640891 is 19804655.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 55640891 - 2¹⁸ = 55378747 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (55640899) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27820445 + 27820446.

It is an arithmetic number, because the mean of its divisors is an integer number (27820446).

Almost surely, 2^55640891 is an apocalyptic number.

55640891 is a deficient number, since it is larger than the sum of its proper divisors (1).

55640891 is an equidigital number, since it uses as much as digits as its factorization.

55640891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 43200, while the sum is 38.

The square root of 55640891 is about 7459.2822040730. The cubic root of 55640891 is about 381.7666836354.

The spelling of 55640891 in words is "fifty-five million, six hundred forty thousand, eight hundred ninety-one".