81992970 has 24 divisors (see below), whose sum is σ = 213181956. Its totient is φ = 21864768.

The previous prime is 81992951. The next prime is 81992971. The reversal of 81992970 is 7929918.

It can be written as a sum of positive squares in 2 ways, for example, as 81054009 + 938961 = 9003^2 + 969^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (81992971) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 455427 + ... + 455606.

Almost surely, 2^81992970 is an apocalyptic number.

81992970 is an abundant number, since it is smaller than the sum of its proper divisors (131188986).

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

81992970 is a wasteful number, since it uses less digits than its factorization.

81992970 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 911046 (or 911043 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 45.

The square root of 81992970 is about 9054.9969630034. The cubic root of 81992970 is about 434.4357328949.

The spelling of 81992970 in words is "eighty-one million, nine hundred ninety-two thousand, nine hundred seventy".