81515628 has 36 divisors (see below), whose sum is σ = 208543608. Its totient is φ = 26843520.

The previous prime is 81515627. The next prime is 81515653. The reversal of 81515628 is 82651518.

81515628 is a `hidden beast` number, since 8 + 15 + 15 + 628 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 81515592 and 81515601.

It is not an unprimeable number, because it can be changed into a prime (81515627) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10653 + ... + 16628.

It is an arithmetic number, because the mean of its divisors is an integer number (5792878).

Almost surely, 2^81515628 is an apocalyptic number.

It is an amenable number.

81515628 is an abundant number, since it is smaller than the sum of its proper divisors (127027980).

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

81515628 is a wasteful number, since it uses less digits than its factorization.

81515628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27374 (or 27369 counting only the distinct ones).

The product of its digits is 19200, while the sum is 36.

The square root of 81515628 is about 9028.6005560109. The cubic root of 81515628 is about 433.5910338306.

The spelling of 81515628 in words is "eighty-one million, five hundred fifteen thousand, six hundred twenty-eight".