81490521 has 32 divisors (see below), whose sum is σ = 127484928. Its totient is φ = 45339840.

The previous prime is 81490517. The next prime is 81490523. The reversal of 81490521 is 12509418.

It is a happy number.

It is not a de Polignac number, because 81490521 - 2² = 81490517 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (81490523) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 234670 + ... + 235016.

It is an arithmetic number, because the mean of its divisors is an integer number (3983904).

Almost surely, 2^81490521 is an apocalyptic number.

It is an amenable number.

81490521 is a deficient number, since it is larger than the sum of its proper divisors (45994407).

81490521 is a wasteful number, since it uses less digits than its factorization.

81490521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 621.

The product of its (nonzero) digits is 2880, while the sum is 30.

The square root of 81490521 is about 9027.2100341135. The cubic root of 81490521 is about 433.5465135825.

Adding to 81490521 its reverse (12509418), we get a palindrome (93999939).

The spelling of 81490521 in words is "eighty-one million, four hundred ninety thousand, five hundred twenty-one".