81213672 has 16 divisors (see below), whose sum is σ = 203034240. Its totient is φ = 27071216.

The previous prime is 81213653. The next prime is 81213673. The reversal of 81213672 is 27631218.

It is not an unprimeable number, because it can be changed into a prime (81213673) 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, 1691928 + ... + 1691975.

It is an arithmetic number, because the mean of its divisors is an integer number (12689640).

Almost surely, 2^81213672 is an apocalyptic number.

It is an amenable number.

81213672 is an abundant number, since it is smaller than the sum of its proper divisors (121820568).

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

81213672 is a wasteful number, since it uses less digits than its factorization.

81213672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3383912 (or 3383908 counting only the distinct ones).

The product of its digits is 4032, while the sum is 30.

The square root of 81213672 is about 9011.8628484903. The cubic root of 81213672 is about 433.0549917978.

The spelling of 81213672 in words is "eighty-one million, two hundred thirteen thousand, six hundred seventy-two".