51021831 has 16 divisors (see below), whose sum is σ = 78624000. Its totient is φ = 28826688.

The previous prime is 51021827. The next prime is 51021833. The reversal of 51021831 is 13812015.

It is not a de Polignac number, because 51021831 - 2² = 51021827 is a prime.

It is a super-2 number, since 2×51021831² = 5206454477185122, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a nialpdrome in base 13.

It is a junction number, because it is equal to n+sod(n) for n = 51021798 and 51021807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51021833) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11781 + ... + 15518.

It is an arithmetic number, because the mean of its divisors is an integer number (4914000).

Almost surely, 2^51021831 is an apocalyptic number.

51021831 is a deficient number, since it is larger than the sum of its proper divisors (27602169).

51021831 is a wasteful number, since it uses less digits than its factorization.

51021831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27398.

The product of its (nonzero) digits is 240, while the sum is 21.

The square root of 51021831 is about 7142.9567407342. The cubic root of 51021831 is about 370.8958835811.

Adding to 51021831 its reverse (13812015), we get a palindrome (64833846).

The spelling of 51021831 in words is "fifty-one million, twenty-one thousand, eight hundred thirty-one".