815138987 has 8 divisors (see below), whose sum is σ = 879409104. Its totient is φ = 751092768.

The previous prime is 815138981. The next prime is 815139019. The reversal of 815138987 is 789831518.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 815138987 - 2¹⁶ = 815073451 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (815138981) 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, 48368 + ... + 63005.

It is an arithmetic number, because the mean of its divisors is an integer number (109926138).

Almost surely, 2^815138987 is an apocalyptic number.

815138987 is a deficient number, since it is larger than the sum of its proper divisors (64270117).

815138987 is a wasteful number, since it uses less digits than its factorization.

815138987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111949.

The product of its digits is 483840, while the sum is 50.

The square root of 815138987 is about 28550.6389946005. The cubic root of 815138987 is about 934.1369587792.

The spelling of 815138987 in words is "eight hundred fifteen million, one hundred thirty-eight thousand, nine hundred eighty-seven".