81905610 has 32 divisors (see below), whose sum is σ = 196813440. Its totient is φ = 21814848.

The previous prime is 81905597. The next prime is 81905623. The reversal of 81905610 is 1650918.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81905597) and next prime (81905623).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42651 + ... + 44529.

It is an arithmetic number, because the mean of its divisors is an integer number (6150420).

Almost surely, 2^81905610 is an apocalyptic number.

81905610 is an abundant number, since it is smaller than the sum of its proper divisors (114907830).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81905610 is a wasteful number, since it uses less digits than its factorization.

81905610 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3342.

The product of its (nonzero) digits is 2160, while the sum is 30.

The square root of 81905610 is about 9050.1718215733. The cubic root of 81905610 is about 434.2813871729.

The spelling of 81905610 in words is "eighty-one million, nine hundred five thousand, six hundred ten".