51621215 has 4 divisors (see below), whose sum is σ = 61945464. Its totient is φ = 41296968.

The previous prime is 51621209. The next prime is 51621217. The reversal of 51621215 is 51212615.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51621215 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51621217) 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, 5162117 + ... + 5162126.

It is an arithmetic number, because the mean of its divisors is an integer number (15486366).

Almost surely, 2^51621215 is an apocalyptic number.

51621215 is a deficient number, since it is larger than the sum of its proper divisors (10324249).

51621215 is a wasteful number, since it uses less digits than its factorization.

51621215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10324248.

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

The square root of 51621215 is about 7184.7905327852. The cubic root of 51621215 is about 372.3426117676.

The spelling of 51621215 in words is "fifty-one million, six hundred twenty-one thousand, two hundred fifteen".