51721791 has 8 divisors (see below), whose sum is σ = 75231744. Its totient is φ = 31346520.

The previous prime is 51721771. The next prime is 51721793. The reversal of 51721791 is 19712715.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 51721791 - 2²³ = 43333183 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 1567327 = 51721791 / (5 + 1 + 7 + 2 + 1 + 7 + 9 + 1).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51721793) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 783631 + ... + 783696.

It is an arithmetic number, because the mean of its divisors is an integer number (9403968).

Almost surely, 2^51721791 is an apocalyptic number.

51721791 is a deficient number, since it is larger than the sum of its proper divisors (23509953).

51721791 is a wasteful number, since it uses less digits than its factorization.

51721791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1567341.

The product of its digits is 4410, while the sum is 33.

The square root of 51721791 is about 7191.7863566711. The cubic root of 51721791 is about 372.5842723315.

The spelling of 51721791 in words is "fifty-one million, seven hundred twenty-one thousand, seven hundred ninety-one".