51440987 has 4 divisors (see below), whose sum is σ = 55398000. Its totient is φ = 47483976.

The previous prime is 51440953. The next prime is 51441001. The reversal of 51440987 is 78904415.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 51440987 - 2⁸ = 51440731 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 51440987.

It is not an unprimeable number, because it can be changed into a prime (51440927) 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, 1978487 + ... + 1978512.

It is an arithmetic number, because the mean of its divisors is an integer number (13849500).

Almost surely, 2^51440987 is an apocalyptic number.

51440987 is a deficient number, since it is larger than the sum of its proper divisors (3957013).

51440987 is a wasteful number, since it uses less digits than its factorization.

51440987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3957012.

The product of its (nonzero) digits is 40320, while the sum is 38.

The square root of 51440987 is about 7172.2372381287. The cubic root of 51440987 is about 371.9087797105.

The spelling of 51440987 in words is "fifty-one million, four hundred forty thousand, nine hundred eighty-seven".