51400640 has 28 divisors (see below), whose sum is σ = 122398536. Its totient is φ = 20560128.

The previous prime is 51400637. The next prime is 51400651. The reversal of 51400640 is 4600415.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 79994 + ... + 80633.

Almost surely, 2^51400640 is an apocalyptic number.

It is an amenable number.

51400640 is an abundant number, since it is smaller than the sum of its proper divisors (70997896).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51400640 is a wasteful number, since it uses less digits than its factorization.

51400640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160644 (or 160634 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 51400640 is about 7169.4239657032. The cubic root of 51400640 is about 371.8115205065.

The spelling of 51400640 in words is "fifty-one million, four hundred thousand, six hundred forty".