81837780 has 24 divisors (see below), whose sum is σ = 229145952. Its totient is φ = 21823392.

The previous prime is 81837757. The next prime is 81837793. The reversal of 81837780 is 8773818.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 681922 + ... + 682041.

It is an arithmetic number, because the mean of its divisors is an integer number (9547748).

Almost surely, 2^81837780 is an apocalyptic number.

It is an amenable number.

81837780 is an abundant number, since it is smaller than the sum of its proper divisors (147308172).

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

81837780 is a wasteful number, since it uses less digits than its factorization.

81837780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1363975 (or 1363973 counting only the distinct ones).

The product of its (nonzero) digits is 75264, while the sum is 42.

The square root of 81837780 is about 9046.4236027283. The cubic root of 81837780 is about 434.1614709184.

The spelling of 81837780 in words is "eighty-one million, eight hundred thirty-seven thousand, seven hundred eighty".