81210013 has 4 divisors (see below), whose sum is σ = 82353888. Its totient is φ = 80066140.

The previous prime is 81210007. The next prime is 81210067. The reversal of 81210013 is 31001218.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81210013 - 2⁹ = 81209501 is a prime.

It is a super-2 number, since 2×81210013² = 13190132422920338, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81210083) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 571831 + ... + 571972.

It is an arithmetic number, because the mean of its divisors is an integer number (20588472).

Almost surely, 2^81210013 is an apocalyptic number.

It is an amenable number.

81210013 is a deficient number, since it is larger than the sum of its proper divisors (1143875).

81210013 is a wasteful number, since it uses less digits than its factorization.

81210013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1143874.

The product of its (nonzero) digits is 48, while the sum is 16.

The square root of 81210013 is about 9011.6598360125. The cubic root of 81210013 is about 433.0484880816.

The spelling of 81210013 in words is "eighty-one million, two hundred ten thousand, thirteen".