81513390 has 32 divisors (see below), whose sum is σ = 223580160. Its totient is φ = 18631584.

The previous prime is 81513379. The next prime is 81513427. The reversal of 81513390 is 9331518.

It is a happy number.

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 pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 193870 + ... + 194289.

It is an arithmetic number, because the mean of its divisors is an integer number (6986880).

Almost surely, 2^81513390 is an apocalyptic number.

81513390 is an abundant number, since it is smaller than the sum of its proper divisors (142066770).

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

81513390 is a wasteful number, since it uses less digits than its factorization.

81513390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 388176.

The product of its (nonzero) digits is 3240, while the sum is 30.

The square root of 81513390 is about 9028.4766156866. The cubic root of 81513390 is about 433.5870657341.

The spelling of 81513390 in words is "eighty-one million, five hundred thirteen thousand, three hundred ninety".