81390186 has 48 divisors (see below), whose sum is σ = 196560000. Its totient is φ = 24188544.

The previous prime is 81390173. The next prime is 81390187. The reversal of 81390186 is 68109318.

It is a super-2 number, since 2×81390186² = 13248724754229192, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81390186.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81390187) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1186 + ... + 12813.

It is an arithmetic number, because the mean of its divisors is an integer number (4095000).

Almost surely, 2^81390186 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81390186, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (98280000).

81390186 is an abundant number, since it is smaller than the sum of its proper divisors (115169814).

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

81390186 is a wasteful number, since it uses less digits than its factorization.

81390186 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14043 (or 14040 counting only the distinct ones).

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

The square root of 81390186 is about 9021.6509575576. The cubic root of 81390186 is about 433.3685061522.

The spelling of 81390186 in words is "eighty-one million, three hundred ninety thousand, one hundred eighty-six".