81437131 has 2 divisors, whose sum is σ = 81437132. Its totient is φ = 81437130.

The previous prime is 81437129. The next prime is 81437137. The reversal of 81437131 is 13173418.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81437131 - 2¹ = 81437129 is a prime.

It is a super-2 number, since 2×81437131² = 13264012611022322, which contains 22 as substring.

Together with 81437129, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 81437131.

It is not a weakly prime, because it can be changed into another prime (81437137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40718565 + 40718566.

It is an arithmetic number, because the mean of its divisors is an integer number (40718566).

Almost surely, 2^81437131 is an apocalyptic number.

81437131 is a deficient number, since it is larger than the sum of its proper divisors (1).

81437131 is an equidigital number, since it uses as much as digits as its factorization.

81437131 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2016, while the sum is 28.

The square root of 81437131 is about 9024.2523790063. The cubic root of 81437131 is about 433.4518109309.

The spelling of 81437131 in words is "eighty-one million, four hundred thirty-seven thousand, one hundred thirty-one".