51031640 has 32 divisors (see below), whose sum is σ = 125260560. Its totient is φ = 18556800.

The previous prime is 51031597. The next prime is 51031649. The reversal of 51031640 is 4613015.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51031649) 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, 57551 + ... + 58430.

Almost surely, 2^51031640 is an apocalyptic number.

It is an amenable number.

51031640 is an abundant number, since it is smaller than the sum of its proper divisors (74228920).

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

51031640 is a wasteful number, since it uses less digits than its factorization.

51031640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116003 (or 115999 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 51031640 is about 7143.6433281625. The cubic root of 51031640 is about 370.9196504310.

Adding to 51031640 its reverse (4613015), we get a palindrome (55644655).

The spelling of 51031640 in words is "fifty-one million, thirty-one thousand, six hundred forty".