81395987 has 16 divisors (see below), whose sum is σ = 86261760. Its totient is φ = 76699200.

The previous prime is 81395971. The next prime is 81395999. The reversal of 81395987 is 78959318.

It is a cyclic number.

It is not a de Polignac number, because 81395987 - 2⁴ = 81395971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81395927) 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, 349223 + ... + 349455.

It is an arithmetic number, because the mean of its divisors is an integer number (5391360).

Almost surely, 2^81395987 is an apocalyptic number.

81395987 is a deficient number, since it is larger than the sum of its proper divisors (4865773).

81395987 is a wasteful number, since it uses less digits than its factorization.

81395987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 514.

The product of its digits is 544320, while the sum is 50.

The square root of 81395987 is about 9021.9724561761. The cubic root of 81395987 is about 433.3788018693.

The spelling of 81395987 in words is "eighty-one million, three hundred ninety-five thousand, nine hundred eighty-seven".