81899619772 has 6 divisors (see below), whose sum is σ = 143324334608. Its totient is φ = 40949809884.

The previous prime is 81899619761. The next prime is 81899619779. The reversal of 81899619772 is 27791699818.

It is a junction number, because it is equal to n+sod(n) for n = 81899619698 and 81899619707.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81899619779) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10237452468 + ... + 10237452475.

Almost surely, 2^81899619772 is an apocalyptic number.

It is an amenable number.

81899619772 is a deficient number, since it is larger than the sum of its proper divisors (61424714836).

81899619772 is a wasteful number, since it uses less digits than its factorization.

81899619772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20474904947 (or 20474904945 counting only the distinct ones).

The product of its digits is 27433728, while the sum is 67.

The spelling of 81899619772 in words is "eighty-one billion, eight hundred ninety-nine million, six hundred nineteen thousand, seven hundred seventy-two".