81837021 has 8 divisors (see below), whose sum is σ = 124704064. Its totient is φ = 46764000.

The previous prime is 81836947. The next prime is 81837053. The reversal of 81837021 is 12073818.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81837021 - 2⁷ = 81836893 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81837021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81837121) 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, 1948480 + ... + 1948521.

It is an arithmetic number, because the mean of its divisors is an integer number (15588008).

Almost surely, 2^81837021 is an apocalyptic number.

It is an amenable number.

81837021 is a deficient number, since it is larger than the sum of its proper divisors (42867043).

81837021 is a wasteful number, since it uses less digits than its factorization.

81837021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3897011.

The product of its (nonzero) digits is 2688, while the sum is 30.

The square root of 81837021 is about 9046.3816523514. The cubic root of 81837021 is about 434.1601287120.

The spelling of 81837021 in words is "eighty-one million, eight hundred thirty-seven thousand, twenty-one".