81438520 has 32 divisors (see below), whose sum is σ = 184064400. Its totient is φ = 32428288.

The previous prime is 81438509. The next prime is 81438523. The reversal of 81438520 is 2583418.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81438523) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4596 + ... + 13564.

Almost surely, 2^81438520 is an apocalyptic number.

It is an amenable number.

81438520 is an abundant number, since it is smaller than the sum of its proper divisors (102625880).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81438520 is a wasteful number, since it uses less digits than its factorization.

81438520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9207 (or 9203 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 31.

The square root of 81438520 is about 9024.3293379619. The cubic root of 81438520 is about 433.4542752496.

The spelling of 81438520 in words is "eighty-one million, four hundred thirty-eight thousand, five hundred twenty".