56491891 has 4 divisors (see below), whose sum is σ = 57869784. Its totient is φ = 55114000.

The previous prime is 56491871. The next prime is 56491937. The reversal of 56491891 is 19819465.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19819465 = 5 ⋅3963893.

It is a cyclic number.

It is not a de Polignac number, because 56491891 - 2¹⁷ = 56360819 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (56491811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 688885 + ... + 688966.

It is an arithmetic number, because the mean of its divisors is an integer number (14467446).

Almost surely, 2^56491891 is an apocalyptic number.

56491891 is a deficient number, since it is larger than the sum of its proper divisors (1377893).

56491891 is a wasteful number, since it uses less digits than its factorization.

56491891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1377892.

The product of its digits is 77760, while the sum is 43.

The square root of 56491891 is about 7516.1087671747. The cubic root of 56491891 is about 383.7031555533.

The spelling of 56491891 in words is "fifty-six million, four hundred ninety-one thousand, eight hundred ninety-one".