51657221 has 24 divisors (see below), whose sum is σ = 65992320. Its totient is φ = 39984000.

The previous prime is 51657197. The next prime is 51657223. The reversal of 51657221 is 12275615.

It is not a de Polignac number, because 51657221 - 2¹⁰ = 51656197 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 (51657223) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 128621 + ... + 129021.

It is an arithmetic number, because the mean of its divisors is an integer number (2749680).

Almost surely, 2^51657221 is an apocalyptic number.

It is an amenable number.

51657221 is a deficient number, since it is larger than the sum of its proper divisors (14335099).

51657221 is a wasteful number, since it uses less digits than its factorization.

51657221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 665 (or 658 counting only the distinct ones).

The product of its digits is 4200, while the sum is 29.

The square root of 51657221 is about 7187.2958057951. The cubic root of 51657221 is about 372.4291617919.

The spelling of 51657221 in words is "fifty-one million, six hundred fifty-seven thousand, two hundred twenty-one".