81331337 has 4 divisors (see below), whose sum is σ = 81374976. Its totient is φ = 81287700.

The previous prime is 81331333. The next prime is 81331339. The reversal of 81331337 is 73313318.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81331337 - 2² = 81331333 is a prime.

It is a super-2 number, since 2×81331337² = 13229572756415138, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81331333) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18893 + ... + 22794.

It is an arithmetic number, because the mean of its divisors is an integer number (20343744).

Almost surely, 2^81331337 is an apocalyptic number.

It is an amenable number.

81331337 is a deficient number, since it is larger than the sum of its proper divisors (43639).

81331337 is a wasteful number, since it uses less digits than its factorization.

81331337 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43638.

The product of its digits is 4536, while the sum is 29.

The square root of 81331337 is about 9018.3888250618. The cubic root of 81331337 is about 433.2640322443.

The spelling of 81331337 in words is "eighty-one million, three hundred thirty-one thousand, three hundred thirty-seven".