81439492 has 6 divisors (see below), whose sum is σ = 142519118. Its totient is φ = 40719744.

The previous prime is 81439483. The next prime is 81439493. The reversal of 81439492 is 29493418.

It can be written as a sum of positive squares in only one way, i.e., 76842756 + 4596736 = 8766^2 + 2144^2 .

It is not an unprimeable number, because it can be changed into a prime (81439493) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10179933 + ... + 10179940.

Almost surely, 2^81439492 is an apocalyptic number.

It is an amenable number.

81439492 is a deficient number, since it is larger than the sum of its proper divisors (61079626).

81439492 is a wasteful number, since it uses less digits than its factorization.

81439492 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20359877 (or 20359875 counting only the distinct ones).

The product of its digits is 62208, while the sum is 40.

The square root of 81439492 is about 9024.3831922187. The cubic root of 81439492 is about 433.4559997238.

The spelling of 81439492 in words is "eighty-one million, four hundred thirty-nine thousand, four hundred ninety-two".