51721969 has 8 divisors (see below), whose sum is σ = 55758080. Its totient is φ = 47694096.

The previous prime is 51721927. The next prime is 51721997. The reversal of 51721969 is 96912715.

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

It is a cyclic number.

It is not a de Polignac number, because 51721969 - 2⁷ = 51721841 is a prime.

It is a super-2 number, since 2×51721969² = 5350324154473922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51721909) 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, 19102 + ... + 21640.

It is an arithmetic number, because the mean of its divisors is an integer number (6969760).

Almost surely, 2^51721969 is an apocalyptic number.

It is an amenable number.

51721969 is a deficient number, since it is larger than the sum of its proper divisors (4036111).

51721969 is a wasteful number, since it uses less digits than its factorization.

51721969 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4119.

The product of its digits is 34020, while the sum is 40.

The square root of 51721969 is about 7191.7987318890. The cubic root of 51721969 is about 372.5846997460.

The spelling of 51721969 in words is "fifty-one million, seven hundred twenty-one thousand, nine hundred sixty-nine".