51151681 has 4 divisors (see below), whose sum is σ = 58459072. Its totient is φ = 43844292.

The previous prime is 51151613. The next prime is 51151687. The reversal of 51151681 is 18615115.

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, and also an emirpimes, since its reverse is a distinct semiprime: 18615115 = 5 ⋅3723023.

It is a cyclic number.

It is not a de Polignac number, because 51151681 - 2¹¹ = 51149633 is a prime.

It is a super-2 number, since 2×51151681² = 5232988938251522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (51151687) 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, 3653685 + ... + 3653698.

It is an arithmetic number, because the mean of its divisors is an integer number (14614768).

Almost surely, 2^51151681 is an apocalyptic number.

It is an amenable number.

51151681 is a deficient number, since it is larger than the sum of its proper divisors (7307391).

51151681 is an equidigital number, since it uses as much as digits as its factorization.

51151681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7307390.

The product of its digits is 1200, while the sum is 28.

The square root of 51151681 is about 7152.0403382531. The cubic root of 51151681 is about 371.2102590223.

Adding to 51151681 its reverse (18615115), we get a palindrome (69766796).

The spelling of 51151681 in words is "fifty-one million, one hundred fifty-one thousand, six hundred eighty-one".