51649881 has 16 divisors (see below), whose sum is σ = 72610944. Its totient is φ = 32592384.

The previous prime is 51649877. The next prime is 51649889. The reversal of 51649881 is 18894615.

It is not a de Polignac number, because 51649881 - 2² = 51649877 is a prime.

It is a super-2 number, since 2×51649881² = 5335420414628322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (51649889) 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, 2835 + ... + 10551.

It is an arithmetic number, because the mean of its divisors is an integer number (4538184).

Almost surely, 2^51649881 is an apocalyptic number.

It is an amenable number.

51649881 is a deficient number, since it is larger than the sum of its proper divisors (20961063).

51649881 is a wasteful number, since it uses less digits than its factorization.

51649881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7840.

The product of its digits is 69120, while the sum is 42.

The square root of 51649881 is about 7186.7851644529. The cubic root of 51649881 is about 372.4115214087.

The spelling of 51649881 in words is "fifty-one million, six hundred forty-nine thousand, eight hundred eighty-one".