51809691 has 16 divisors (see below), whose sum is σ = 71009568. Its totient is φ = 33580800.

The previous prime is 51809687. The next prime is 51809707. The reversal of 51809691 is 19690815.

It is not a de Polignac number, because 51809691 - 2² = 51809687 is a prime.

It is not an unprimeable number, because it can be changed into a prime (51809671) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 48301 + ... + 49361.

It is an arithmetic number, because the mean of its divisors is an integer number (4438098).

Almost surely, 2^51809691 is an apocalyptic number.

51809691 is a deficient number, since it is larger than the sum of its proper divisors (19199877).

51809691 is a wasteful number, since it uses less digits than its factorization.

51809691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1502.

The product of its (nonzero) digits is 19440, while the sum is 39.

The square root of 51809691 is about 7197.8949005942. The cubic root of 51809691 is about 372.7952190247.

The spelling of 51809691 in words is "fifty-one million, eight hundred nine thousand, six hundred ninety-one".