51697681 has 8 divisors (see below), whose sum is σ = 59131904. Its totient is φ = 44275680.

The previous prime is 51697673. The next prime is 51697687. The reversal of 51697681 is 18679615.

It is a happy number.

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 51697681 - 2³ = 51697673 is a prime.

It is a super-2 number, since 2×51697681² = 5345300441555522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51697687) 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, 9421 + ... + 13861.

It is an arithmetic number, because the mean of its divisors is an integer number (7391488).

Almost surely, 2^51697681 is an apocalyptic number.

It is an amenable number.

51697681 is a deficient number, since it is larger than the sum of its proper divisors (7434223).

51697681 is a wasteful number, since it uses less digits than its factorization.

51697681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6111.

The product of its digits is 90720, while the sum is 43.

The square root of 51697681 is about 7190.1099435266. The cubic root of 51697681 is about 372.5263702185.

The spelling of 51697681 in words is "fifty-one million, six hundred ninety-seven thousand, six hundred eighty-one".