51500381 has 4 divisors (see below), whose sum is σ = 53739552. Its totient is φ = 49261212.

The previous prime is 51500377. The next prime is 51500389. The reversal of 51500381 is 18300515.

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 51500381 - 2² = 51500377 is a prime.

It is a super-2 number, since 2×51500381² = 5304578486290322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (23), and also a Moran number because the ratio is a prime number: 2239147 = 51500381 / (5 + 1 + 5 + 0 + 0 + 3 + 8 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51500389) 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, 1119551 + ... + 1119596.

It is an arithmetic number, because the mean of its divisors is an integer number (13434888).

Almost surely, 2^51500381 is an apocalyptic number.

It is an amenable number.

51500381 is a deficient number, since it is larger than the sum of its proper divisors (2239171).

51500381 is a wasteful number, since it uses less digits than its factorization.

51500381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2239170.

The product of its (nonzero) digits is 600, while the sum is 23.

The square root of 51500381 is about 7176.3765926824. The cubic root of 51500381 is about 372.0518605194.

Adding to 51500381 its reverse (18300515), we get a palindrome (69800896).

The spelling of 51500381 in words is "fifty-one million, five hundred thousand, three hundred eighty-one".