51721407 has 12 divisors (see below), whose sum is σ = 74809800. Its totient is φ = 34434288.

The previous prime is 51721399. The next prime is 51721409. The reversal of 51721407 is 70412715.

51721407 is a `hidden beast` number, since 517 + 2 + 140 + 7 = 666.

It is not a de Polignac number, because 51721407 - 2³ = 51721399 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51721409) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3969 + ... + 10917.

It is an arithmetic number, because the mean of its divisors is an integer number (6234150).

Almost surely, 2^51721407 is an apocalyptic number.

51721407 is a deficient number, since it is larger than the sum of its proper divisors (23088393).

51721407 is a wasteful number, since it uses less digits than its factorization.

51721407 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7782 (or 7779 counting only the distinct ones).

The product of its (nonzero) digits is 1960, while the sum is 27.

The square root of 51721407 is about 7191.7596594992. The cubic root of 51721407 is about 372.5833502655.

The spelling of 51721407 in words is "fifty-one million, seven hundred twenty-one thousand, four hundred seven".