81389616 has 240 divisors, whose sum is σ = 281196288. Its totient is φ = 19699200.

The previous prime is 81389599. The next prime is 81389639. The reversal of 81389616 is 61698318.

It is a Harshad number since it is a multiple of its sum of digits (42).

Its product of digits (62208) is a multiple of the sum of its prime factors (128).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1334226 + ... + 1334286.

Almost surely, 2^81389616 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81389616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (140598144).

81389616 is an abundant number, since it is smaller than the sum of its proper divisors (199806672).

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

81389616 is a wasteful number, since it uses less digits than its factorization.

81389616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128 (or 103 counting only the distinct ones).

The product of its digits is 62208, while the sum is 42.

The square root of 81389616 is about 9021.6193668321. The cubic root of 81389616 is about 433.3674944798.

The spelling of 81389616 in words is "eighty-one million, three hundred eighty-nine thousand, six hundred sixteen".