81331437 has 8 divisors (see below), whose sum is σ = 118300320. Its totient is φ = 49291760.

The previous prime is 81331433. The next prime is 81331463. The reversal of 81331437 is 73413318.

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

It is a cyclic number.

It is not a de Polignac number, because 81331437 - 2² = 81331433 is a prime.

It is a super-2 number, since 2×81331437² = 13229605288969938, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81331433) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1232262 + ... + 1232327.

It is an arithmetic number, because the mean of its divisors is an integer number (14787540).

Almost surely, 2^81331437 is an apocalyptic number.

It is an amenable number.

81331437 is a deficient number, since it is larger than the sum of its proper divisors (36968883).

81331437 is a wasteful number, since it uses less digits than its factorization.

81331437 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2464603.

The product of its digits is 6048, while the sum is 30.

The square root of 81331437 is about 9018.3943692877. The cubic root of 81331437 is about 433.2642098158.

The spelling of 81331437 in words is "eighty-one million, three hundred thirty-one thousand, four hundred thirty-seven".