81239437 has 8 divisors (see below), whose sum is σ = 85011200. Its totient is φ = 77539680.

The previous prime is 81239423. The next prime is 81239449. The reversal of 81239437 is 73493218.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81239437 - 2¹⁵ = 81206669 is a prime.

It is a super-2 number, since 2×81239437² = 13199692248153938, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81239396 and 81239405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81237437) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15687 + ... + 20212.

It is an arithmetic number, because the mean of its divisors is an integer number (10626400).

Almost surely, 2^81239437 is an apocalyptic number.

It is an amenable number.

81239437 is a deficient number, since it is larger than the sum of its proper divisors (3771763).

81239437 is a wasteful number, since it uses less digits than its factorization.

81239437 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36003.

The product of its digits is 36288, while the sum is 37.

The square root of 81239437 is about 9013.2922397978. The cubic root of 81239437 is about 433.1007824546.

The spelling of 81239437 in words is "eighty-one million, two hundred thirty-nine thousand, four hundred thirty-seven".