81521308 has 24 divisors (see below), whose sum is σ = 156636144. Its totient is φ = 36816000.

The previous prime is 81521299. The next prime is 81521309. The reversal of 81521308 is 80312518.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81521309) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1008 + ... + 12808.

It is an arithmetic number, because the mean of its divisors is an integer number (6526506).

Almost surely, 2^81521308 is an apocalyptic number.

It is an amenable number.

81521308 is a deficient number, since it is larger than the sum of its proper divisors (75114836).

81521308 is a wasteful number, since it uses less digits than its factorization.

81521308 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11973 (or 11971 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 28.

The square root of 81521308 is about 9028.9151064787. The cubic root of 81521308 is about 433.6011044552.

The spelling of 81521308 in words is "eighty-one million, five hundred twenty-one thousand, three hundred eight".