81250005 has 32 divisors (see below), whose sum is σ = 134424576. Its totient is φ = 41880384.

The previous prime is 81249997. The next prime is 81250019. The reversal of 81250005 is 50005218.

It is not a de Polignac number, because 81250005 - 2³ = 81249997 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 65824 + ... + 67046.

It is an arithmetic number, because the mean of its divisors is an integer number (4200768).

Almost surely, 2^81250005 is an apocalyptic number.

It is an amenable number.

81250005 is a deficient number, since it is larger than the sum of its proper divisors (53174571).

81250005 is a wasteful number, since it uses less digits than its factorization.

81250005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1377.

The product of its (nonzero) digits is 400, while the sum is 21.

The square root of 81250005 is about 9013.8784660101. The cubic root of 81250005 is about 433.1195615550.

The spelling of 81250005 in words is "eighty-one million, two hundred fifty thousand, five".