51355991 has 2 divisors, whose sum is σ = 51355992. Its totient is φ = 51355990.

The previous prime is 51355981. The next prime is 51355999. The reversal of 51355991 is 19955315.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51355991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51355999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25677995 + 25677996.

It is an arithmetic number, because the mean of its divisors is an integer number (25677996).

Almost surely, 2^51355991 is an apocalyptic number.

51355991 is a deficient number, since it is larger than the sum of its proper divisors (1).

51355991 is an equidigital number, since it uses as much as digits as its factorization.

51355991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30375, while the sum is 38.

The square root of 51355991 is about 7166.3094407094. The cubic root of 51355991 is about 371.7038316937.

The spelling of 51355991 in words is "fifty-one million, three hundred fifty-five thousand, nine hundred ninety-one".