51157681 has 4 divisors (see below), whose sum is σ = 53381952. Its totient is φ = 48933412.

The previous prime is 51157669. The next prime is 51157697. The reversal of 51157681 is 18675115.

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 51157681 - 2¹¹ = 51155633 is a prime.

It is a super-2 number, since 2×51157681² = 5234216650595522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51157621) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1112101 + ... + 1112146.

It is an arithmetic number, because the mean of its divisors is an integer number (13345488).

Almost surely, 2^51157681 is an apocalyptic number.

It is an amenable number.

51157681 is a deficient number, since it is larger than the sum of its proper divisors (2224271).

51157681 is a wasteful number, since it uses less digits than its factorization.

51157681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2224270.

The product of its digits is 8400, while the sum is 34.

The square root of 51157681 is about 7152.4597866748. The cubic root of 51157681 is about 371.2247725529.

The spelling of 51157681 in words is "fifty-one million, one hundred fifty-seven thousand, six hundred eighty-one".