81490942821 has 16 divisors (see below), whose sum is σ = 112226992640. Its totient is φ = 52543200960.

The previous prime is 81490942751. The next prime is 81490942837. The reversal of 81490942821 is 12824909418.

It is not a de Polignac number, because 81490942821 - 2⁷ = 81490942693 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81490942021) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 107290 + ... + 417723.

It is an arithmetic number, because the mean of its divisors is an integer number (7014187040).

Almost surely, 2^81490942821 is an apocalyptic number.

It is an amenable number.

81490942821 is a deficient number, since it is larger than the sum of its proper divisors (30736049819).

81490942821 is a wasteful number, since it uses less digits than its factorization.

81490942821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 526716.

The product of its (nonzero) digits is 331776, while the sum is 48.

The spelling of 81490942821 in words is "eighty-one billion, four hundred ninety million, nine hundred forty-two thousand, eight hundred twenty-one".