81939562 has 4 divisors (see below), whose sum is σ = 122909346. Its totient is φ = 40969780.

The previous prime is 81939503. The next prime is 81939569. The reversal of 81939562 is 26593918.

It is a happy number.

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., 50253921 + 31685641 = 7089^2 + 5629^2 .

It is not an unprimeable number, because it can be changed into a prime (81939569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20484889 + ... + 20484892.

Almost surely, 2^81939562 is an apocalyptic number.

81939562 is a deficient number, since it is larger than the sum of its proper divisors (40969784).

81939562 is a wasteful number, since it uses less digits than its factorization.

81939562 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40969783.

The product of its digits is 116640, while the sum is 43.

The square root of 81939562 is about 9052.0473927173. The cubic root of 81939562 is about 434.3413858501.

The spelling of 81939562 in words is "eighty-one million, nine hundred thirty-nine thousand, five hundred sixty-two".