81306870 has 32 divisors (see below), whose sum is σ = 195678720. Its totient is φ = 21621600.

The previous prime is 81306859. The next prime is 81306877. The reversal of 81306870 is 7860318.

It is a super-2 number, since 2×81306870² = 13221614218393800, 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 (81306877) 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, 7795 + ... + 14945.

It is an arithmetic number, because the mean of its divisors is an integer number (6114960).

Almost surely, 2^81306870 is an apocalyptic number.

81306870 is an abundant number, since it is smaller than the sum of its proper divisors (114371850).

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

81306870 is a wasteful number, since it uses less digits than its factorization.

81306870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7540.

The product of its (nonzero) digits is 8064, while the sum is 33.

The square root of 81306870 is about 9017.0322168660. The cubic root of 81306870 is about 433.2205814473.

The spelling of 81306870 in words is "eighty-one million, three hundred six thousand, eight hundred seventy".