51891491 has 2 divisors, whose sum is σ = 51891492. Its totient is φ = 51891490.

The previous prime is 51891487. The next prime is 51891493. The reversal of 51891491 is 19419815.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 51891491 - 2² = 51891487 is a prime.

Together with 51891493, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (51891493) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25945745 + 25945746.

It is an arithmetic number, because the mean of its divisors is an integer number (25945746).

Almost surely, 2^51891491 is an apocalyptic number.

51891491 is a deficient number, since it is larger than the sum of its proper divisors (1).

51891491 is an equidigital number, since it uses as much as digits as its factorization.

51891491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12960, while the sum is 38.

The square root of 51891491 is about 7203.5748764069. The cubic root of 51891491 is about 372.9913124164.

The spelling of 51891491 in words is "fifty-one million, eight hundred ninety-one thousand, four hundred ninety-one".