181720021372 has 6 divisors (see below), whose sum is σ = 318010037408. Its totient is φ = 90860010684.

The previous prime is 181720021367. The next prime is 181720021403. The reversal of 181720021372 is 273120027181.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 22715002668 + ... + 22715002675.

Almost surely, 2^181720021372 is an apocalyptic number.

It is an amenable number.

181720021372 is a deficient number, since it is larger than the sum of its proper divisors (136290016036).

181720021372 is a wasteful number, since it uses less digits than its factorization.

181720021372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45430005347 (or 45430005345 counting only the distinct ones).

The product of its (nonzero) digits is 9408, while the sum is 34.

The spelling of 181720021372 in words is "one hundred eighty-one billion, seven hundred twenty million, twenty-one thousand, three hundred seventy-two".