81951380 has 24 divisors (see below), whose sum is σ = 196683648. Its totient is φ = 28097568.

The previous prime is 81951379. The next prime is 81951403. The reversal of 81951380 is 8315918.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 81951380.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 292544 + ... + 292823.

It is an arithmetic number, because the mean of its divisors is an integer number (8195152).

Almost surely, 2^81951380 is an apocalyptic number.

It is an amenable number.

81951380 is an abundant number, since it is smaller than the sum of its proper divisors (114732268).

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

81951380 is a wasteful number, since it uses less digits than its factorization.

81951380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 585383 (or 585381 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 35.

The square root of 81951380 is about 9052.7001496791. The cubic root of 81951380 is about 434.3622662796.

The spelling of 81951380 in words is "eighty-one million, nine hundred fifty-one thousand, three hundred eighty".