81437139 has 12 divisors (see below), whose sum is σ = 134436016. Its totient is φ = 46535472.

The previous prime is 81437137. The next prime is 81437159. The reversal of 81437139 is 93173418.

It is a happy number.

It is not a de Polignac number, because 81437139 - 2¹ = 81437137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81437131) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 646264 + ... + 646389.

Almost surely, 2^81437139 is an apocalyptic number.

81437139 is a deficient number, since it is larger than the sum of its proper divisors (52998877).

81437139 is a wasteful number, since it uses less digits than its factorization.

81437139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1292666 (or 1292663 counting only the distinct ones).

The product of its digits is 18144, while the sum is 36.

The square root of 81437139 is about 9024.2528222563. The cubic root of 81437139 is about 433.4518251243.

The spelling of 81437139 in words is "eighty-one million, four hundred thirty-seven thousand, one hundred thirty-nine".