87312981 has 16 divisors (see below), whose sum is σ = 135880704. Its totient is φ = 48831024.

The previous prime is 87312971. The next prime is 87312983. The reversal of 87312981 is 18921378.

It is not a de Polignac number, because 87312981 - 2⁶ = 87312917 is a prime.

It is a super-2 number, since 2×87312981² = 15247113302212722, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87312983) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 43245 + ... + 45218.

It is an arithmetic number, because the mean of its divisors is an integer number (8492544).

Almost surely, 2^87312981 is an apocalyptic number.

It is an amenable number.

87312981 is a deficient number, since it is larger than the sum of its proper divisors (48567723).

87312981 is a wasteful number, since it uses less digits than its factorization.

87312981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88520.

The product of its digits is 24192, while the sum is 39.

The square root of 87312981 is about 9344.1415336028. The cubic root of 87312981 is about 443.6354801750.

The spelling of 87312981 in words is "eighty-seven million, three hundred twelve thousand, nine hundred eighty-one".