81628815 has 16 divisors (see below), whose sum is σ = 138289248. Its totient is φ = 40974336.

The previous prime is 81628793. The next prime is 81628829. The reversal of 81628815 is 51882618.

It is not a de Polignac number, because 81628815 - 2⁵ = 81628783 is a prime.

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, 159802 + ... + 160311.

It is an arithmetic number, because the mean of its divisors is an integer number (8643078).

Almost surely, 2^81628815 is an apocalyptic number.

81628815 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

81628815 is a deficient number, since it is larger than the sum of its proper divisors (56660433).

81628815 is a wasteful number, since it uses less digits than its factorization.

81628815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320138.

The product of its digits is 30720, while the sum is 39.

The square root of 81628815 is about 9034.8666287887. The cubic root of 81628815 is about 433.7916259221.

The spelling of 81628815 in words is "eighty-one million, six hundred twenty-eight thousand, eight hundred fifteen".