81439922 has 4 divisors (see below), whose sum is σ = 122159886. Its totient is φ = 40719960.

The previous prime is 81439903. The next prime is 81439931. The reversal of 81439922 is 22993418.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 65431921 + 16008001 = 8089^2 + 4001^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20359979 + ... + 20359982.

Almost surely, 2^81439922 is an apocalyptic number.

81439922 is a deficient number, since it is larger than the sum of its proper divisors (40719964).

81439922 is a wasteful number, since it uses less digits than its factorization.

81439922 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40719963.

The product of its digits is 31104, while the sum is 38.

The square root of 81439922 is about 9024.4070165302. The cubic root of 81439922 is about 433.4567626041.

The spelling of 81439922 in words is "eighty-one million, four hundred thirty-nine thousand, nine hundred twenty-two".