81587801 has 4 divisors (see below), whose sum is σ = 81913104. Its totient is φ = 81262500.

The previous prime is 81587797. The next prime is 81587819. The reversal of 81587801 is 10878518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81587801 - 2² = 81587797 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81587851) 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, 162275 + ... + 162776.

It is an arithmetic number, because the mean of its divisors is an integer number (20478276).

Almost surely, 2^81587801 is an apocalyptic number.

81587801 is the 4040-th centered decagonal number.

It is an amenable number.

81587801 is a deficient number, since it is larger than the sum of its proper divisors (325303).

81587801 is a wasteful number, since it uses less digits than its factorization.

81587801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 325302.

The product of its (nonzero) digits is 17920, while the sum is 38.

The square root of 81587801 is about 9032.5965812716. The cubic root of 81587801 is about 433.7189615885.

The spelling of 81587801 in words is "eighty-one million, five hundred eighty-seven thousand, eight hundred one".