23198640721 has 3 divisors (see below), whose sum is σ = 23198793033. Its totient is φ = 23198488410.

The previous prime is 23198640713. The next prime is 23198640733. The reversal of 23198640721 is 12704689132.

The square root of 23198640721 is 152311.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 23198640721 - 2³ = 23198640713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (23198640761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 76156 + ... + 228466.

It is an arithmetic number, because the mean of its divisors is an integer number (7732931011).

Almost surely, 2^23198640721 is an apocalyptic number.

23198640721 is the 152311-st square number.

23198640721 is the 76156-th centered octagonal number.

It is an amenable number.

23198640721 is a deficient number, since it is larger than the sum of its proper divisors (152312).

23198640721 is an frugal number, since it uses more digits than its factorization.

23198640721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 304622 (or 152311 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 43.

The spelling of 23198640721 in words is "twenty-three billion, one hundred ninety-eight million, six hundred forty thousand, seven hundred twenty-one".