81121724104 has 16 divisors (see below), whose sum is σ = 154973105820. Its totient is φ = 39795562560.

The previous prime is 81121724077. The next prime is 81121724161. The reversal of 81121724104 is 40142712118.

It can be written as a sum of positive squares in 2 ways, for example, as 65295580900 + 15826143204 = 255530^2 + 125802^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 95661987 + ... + 95662834.

Almost surely, 2^81121724104 is an apocalyptic number.

It is an amenable number.

81121724104 is a deficient number, since it is larger than the sum of its proper divisors (73851381716).

81121724104 is a wasteful number, since it uses less digits than its factorization.

81121724104 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 191324880 (or 191324876 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 31.

The spelling of 81121724104 in words is "eighty-one billion, one hundred twenty-one million, seven hundred twenty-four thousand, one hundred four".