81378520 has 32 divisors (see below), whose sum is σ = 192740400. Its totient is φ = 30837888.

The previous prime is 81378511. The next prime is 81378527. The reversal of 81378520 is 2587318.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81378527) 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, 52779 + ... + 54298.

Almost surely, 2^81378520 is an apocalyptic number.

It is an amenable number.

81378520 is an abundant number, since it is smaller than the sum of its proper divisors (111361880).

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

81378520 is a wasteful number, since it uses less digits than its factorization.

81378520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107107 (or 107103 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 34.

The square root of 81378520 is about 9021.0043786709. The cubic root of 81378520 is about 433.3477996485.

The spelling of 81378520 in words is "eighty-one million, three hundred seventy-eight thousand, five hundred twenty".