81813690 has 96 divisors (see below), whose sum is σ = 257437440. Its totient is φ = 17597952.

The previous prime is 81813689. The next prime is 81813703. The reversal of 81813690 is 9631818.

It is a super-2 number, since 2×81813690² = 13386959742832200, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 6891 + ... + 14529.

It is an arithmetic number, because the mean of its divisors is an integer number (2681640).

Almost surely, 2^81813690 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81813690, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128718720).

81813690 is an abundant number, since it is smaller than the sum of its proper divisors (175623750).

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

81813690 is a wasteful number, since it uses less digits than its factorization.

81813690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7676 (or 7673 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 81813690 is about 9045.0920393327. The cubic root of 81813690 is about 434.1188664056.

The spelling of 81813690 in words is "eighty-one million, eight hundred thirteen thousand, six hundred ninety".