51353991 has 24 divisors (see below), whose sum is σ = 84586320. Its totient is φ = 29742336.

The previous prime is 51353987. The next prime is 51353993. The reversal of 51353991 is 19935315.

51353991 is a `hidden beast` number, since 513 + 53 + 9 + 91 = 666.

It is not a de Polignac number, because 51353991 - 2² = 51353987 is a prime.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51353993) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10921 + ... + 14898.

It is an arithmetic number, because the mean of its divisors is an integer number (3524430).

Almost surely, 2^51353991 is an apocalyptic number.

51353991 is a gapful number since it is divisible by the number (51) formed by its first and last digit.

51353991 is a deficient number, since it is larger than the sum of its proper divisors (33232329).

51353991 is a wasteful number, since it uses less digits than its factorization.

51353991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25855 (or 25852 counting only the distinct ones).

The product of its digits is 18225, while the sum is 36.

The square root of 51353991 is about 7166.1698975115. The cubic root of 51353991 is about 371.6990064383.

The spelling of 51353991 in words is "fifty-one million, three hundred fifty-three thousand, nine hundred ninety-one".