81438237 has 16 divisors (see below), whose sum is σ = 127000000. Its totient is φ = 51434352.

The previous prime is 81438229. The next prime is 81438281. The reversal of 81438237 is 73283418.

It is not a de Polignac number, because 81438237 - 2³ = 81438229 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81438037) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 78862 + ... + 79887.

It is an arithmetic number, because the mean of its divisors is an integer number (7937500).

Almost surely, 2^81438237 is an apocalyptic number.

It is an amenable number.

81438237 is a deficient number, since it is larger than the sum of its proper divisors (45561763).

81438237 is a wasteful number, since it uses less digits than its factorization.

81438237 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158777 (or 158771 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The square root of 81438237 is about 9024.3136581127. The cubic root of 81438237 is about 433.4537731625.

The spelling of 81438237 in words is "eighty-one million, four hundred thirty-eight thousand, two hundred thirty-seven".