51811397 has 4 divisors (see below), whose sum is σ = 56521536. Its totient is φ = 47101260.

The previous prime is 51811379. The next prime is 51811399. The reversal of 51811397 is 79311815.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 51811397 - 2²² = 47617093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51811399) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2355053 + ... + 2355074.

It is an arithmetic number, because the mean of its divisors is an integer number (14130384).

Almost surely, 2^51811397 is an apocalyptic number.

51811397 is the 3848-th centered heptagonal number.

It is an amenable number.

51811397 is a deficient number, since it is larger than the sum of its proper divisors (4710139).

51811397 is a wasteful number, since it uses less digits than its factorization.

51811397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4710138.

The product of its digits is 7560, while the sum is 35.

The square root of 51811397 is about 7198.0134064893. The cubic root of 51811397 is about 372.7993108052.

The spelling of 51811397 in words is "fifty-one million, eight hundred eleven thousand, three hundred ninety-seven".