51020621 has 4 divisors (see below), whose sum is σ = 54021852. Its totient is φ = 48019392.

The previous prime is 51020617. The next prime is 51020653. The reversal of 51020621 is 12602015.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 20340100 + 30680521 = 4510^2 + 5539^2 .

It is a cyclic number.

It is not a de Polignac number, because 51020621 - 2² = 51020617 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 3001213 = 51020621 / (5 + 1 + 0 + 2 + 0 + 6 + 2 + 1).

It is a self number, because there is not a number n which added to its sum of digits gives 51020621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51026621) 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, 1500590 + ... + 1500623.

It is an arithmetic number, because the mean of its divisors is an integer number (13505463).

Almost surely, 2^51020621 is an apocalyptic number.

It is an amenable number.

51020621 is a deficient number, since it is larger than the sum of its proper divisors (3001231).

51020621 is a wasteful number, since it uses less digits than its factorization.

51020621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3001230.

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 51020621 is about 7142.8720414130. The cubic root of 51020621 is about 370.8929515841.

Adding to 51020621 its reverse (12602015), we get a palindrome (63622636).

The spelling of 51020621 in words is "fifty-one million, twenty thousand, six hundred twenty-one".