51621321 has 4 divisors (see below), whose sum is σ = 68828432. Its totient is φ = 34414212.

The previous prime is 51621319. The next prime is 51621329. The reversal of 51621321 is 12312615.

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 not a de Polignac number, because 51621321 - 2¹ = 51621319 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51621329) 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, 8603551 + ... + 8603556.

It is an arithmetic number, because the mean of its divisors is an integer number (17207108).

Almost surely, 2^51621321 is an apocalyptic number.

It is an amenable number.

51621321 is a deficient number, since it is larger than the sum of its proper divisors (17207111).

51621321 is a wasteful number, since it uses less digits than its factorization.

51621321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17207110.

The product of its digits is 360, while the sum is 21.

The square root of 51621321 is about 7184.7979094753. The cubic root of 51621321 is about 372.3428666260.

Adding to 51621321 its reverse (12312615), we get a palindrome (63933936).

The spelling of 51621321 in words is "fifty-one million, six hundred twenty-one thousand, three hundred twenty-one".