81337780 has 24 divisors (see below), whose sum is σ = 171760680. Its totient is φ = 32353920.

The previous prime is 81337771. The next prime is 81337783. The reversal of 81337780 is 8773318.

It can be written as a sum of positive squares in 4 ways, for example, as 1127844 + 80209936 = 1062^2 + 8956^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81337783) 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, 7615 + ... + 14854.

It is an arithmetic number, because the mean of its divisors is an integer number (7156695).

Almost surely, 2^81337780 is an apocalyptic number.

It is an amenable number.

81337780 is an abundant number, since it is smaller than the sum of its proper divisors (90422900).

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

81337780 is a wasteful number, since it uses less digits than its factorization.

81337780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22659 (or 22657 counting only the distinct ones).

The product of its (nonzero) digits is 28224, while the sum is 37.

The square root of 81337780 is about 9018.7460325702. The cubic root of 81337780 is about 433.2754728794.

The spelling of 81337780 in words is "eighty-one million, three hundred thirty-seven thousand, seven hundred eighty".