21801972193 has 4 divisors (see below), whose sum is σ = 21879011248. Its totient is φ = 21724933140.

The previous prime is 21801972163. The next prime is 21801972217. The reversal of 21801972193 is 39127910812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21801972193 - 2¹³ = 21801964001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21801972163) 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, 38519103 + ... + 38519668.

It is an arithmetic number, because the mean of its divisors is an integer number (5469752812).

Almost surely, 2^21801972193 is an apocalyptic number.

It is an amenable number.

21801972193 is a deficient number, since it is larger than the sum of its proper divisors (77039055).

21801972193 is an equidigital number, since it uses as much as digits as its factorization.

21801972193 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77039054.

The product of its (nonzero) digits is 54432, while the sum is 43.

The spelling of 21801972193 in words is "twenty-one billion, eight hundred one million, nine hundred seventy-two thousand, one hundred ninety-three".