51491357 has 2 divisors, whose sum is σ = 51491358. Its totient is φ = 51491356.

The previous prime is 51491287. The next prime is 51491359. The reversal of 51491357 is 75319415.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 47251876 + 4239481 = 6874^2 + 2059^2 .

It is a cyclic number.

It is not a de Polignac number, because 51491357 - 2⁸ = 51491101 is a prime.

Together with 51491359, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51491359) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25745678 + 25745679.

It is an arithmetic number, because the mean of its divisors is an integer number (25745679).

Almost surely, 2^51491357 is an apocalyptic number.

It is an amenable number.

51491357 is a deficient number, since it is larger than the sum of its proper divisors (1).

51491357 is an equidigital number, since it uses as much as digits as its factorization.

51491357 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18900, while the sum is 35.

The square root of 51491357 is about 7175.7478355918. The cubic root of 51491357 is about 372.0301286925.

The spelling of 51491357 in words is "fifty-one million, four hundred ninety-one thousand, three hundred fifty-seven".