81251655188 has 12 divisors (see below), whose sum is σ = 155116796352. Its totient is φ = 36932570520.

The previous prime is 81251655181. The next prime is 81251655257. The reversal of 81251655188 is 88155615218.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81251655181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 923314220 + ... + 923314307.

It is an arithmetic number, because the mean of its divisors is an integer number (12926399696).

Almost surely, 2^81251655188 is an apocalyptic number.

It is an amenable number.

81251655188 is a deficient number, since it is larger than the sum of its proper divisors (73865141164).

81251655188 is a wasteful number, since it uses less digits than its factorization.

81251655188 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1846628542 (or 1846628540 counting only the distinct ones).

The product of its digits is 768000, while the sum is 50.

The spelling of 81251655188 in words is "eighty-one billion, two hundred fifty-one million, six hundred fifty-five thousand, one hundred eighty-eight".