81837820 has 48 divisors (see below), whose sum is σ = 175986720. Its totient is φ = 31958784.

The previous prime is 81837817. The next prime is 81837839. The reversal of 81837820 is 2873818.

It is a self number, because there is not a number n which added to its sum of digits gives 81837820.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 210186 + ... + 210574.

It is an arithmetic number, because the mean of its divisors is an integer number (3666390).

Almost surely, 2^81837820 is an apocalyptic number.

It is an amenable number.

81837820 is an abundant number, since it is smaller than the sum of its proper divisors (94148900).

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

81837820 is a wasteful number, since it uses less digits than its factorization.

81837820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 622 (or 620 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 37.

The square root of 81837820 is about 9046.4258135465. The cubic root of 81837820 is about 434.1615416537.

The spelling of 81837820 in words is "eighty-one million, eight hundred thirty-seven thousand, eight hundred twenty".