51409681 has 4 divisors (see below), whose sum is σ = 52503552. Its totient is φ = 50315812.

The previous prime is 51409643. The next prime is 51409691. The reversal of 51409681 is 18690415.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51409681 is a prime.

It is a super-2 number, since 2×51409681² = 5285910601043522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51409601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 546865 + ... + 546958.

It is an arithmetic number, because the mean of its divisors is an integer number (13125888).

Almost surely, 2^51409681 is an apocalyptic number.

It is an amenable number.

51409681 is a deficient number, since it is larger than the sum of its proper divisors (1093871).

51409681 is a wasteful number, since it uses less digits than its factorization.

51409681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1093870.

The product of its (nonzero) digits is 8640, while the sum is 34.

The square root of 51409681 is about 7170.0544628336. The cubic root of 51409681 is about 371.8333188790.

The spelling of 51409681 in words is "fifty-one million, four hundred nine thousand, six hundred eighty-one".