51387440 has 40 divisors (see below), whose sum is σ = 128668848. Its totient is φ = 18973440.

The previous prime is 51387397. The next prime is 51387509. The reversal of 51387440 is 4478315.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 51387397 and 51387406.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23666 + ... + 25745.

Almost surely, 2^51387440 is an apocalyptic number.

It is an amenable number.

51387440 is an abundant number, since it is smaller than the sum of its proper divisors (77281408).

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

51387440 is a wasteful number, since it uses less digits than its factorization.

51387440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49437 (or 49431 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 32.

The square root of 51387440 is about 7168.5033305426. The cubic root of 51387440 is about 371.7796899544.

The spelling of 51387440 in words is "fifty-one million, three hundred eighty-seven thousand, four hundred forty".