81186420 has 48 divisors (see below), whose sum is σ = 259797888. Its totient is φ = 18556800.

The previous prime is 81186403. The next prime is 81186431. The reversal of 81186420 is 2468118.

It is a Harshad number since it is a multiple of its sum of digits (30).

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, 96231 + ... + 97070.

It is an arithmetic number, because the mean of its divisors is an integer number (5412456).

Almost surely, 2^81186420 is an apocalyptic number.

It is an amenable number.

81186420 is an abundant number, since it is smaller than the sum of its proper divisors (178611468).

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

81186420 is a wasteful number, since it uses less digits than its factorization.

81186420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193320 (or 193318 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 30.

The square root of 81186420 is about 9010.3507145949. The cubic root of 81186420 is about 433.0065478407.

The spelling of 81186420 in words is "eighty-one million, one hundred eighty-six thousand, four hundred twenty".