21801972163 has 2 divisors, whose sum is σ = 21801972164. Its totient is φ = 21801972162.

The previous prime is 21801972079. The next prime is 21801972217. The reversal of 21801972163 is 36127910812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21801972163 - 2²¹ = 21799875011 is a prime.

It is not a weakly prime, because it can be changed into another prime (21801979163) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10900986081 + 10900986082.

It is an arithmetic number, because the mean of its divisors is an integer number (10900986082).

Almost surely, 2^21801972163 is an apocalyptic number.

21801972163 is a deficient number, since it is larger than the sum of its proper divisors (1).

21801972163 is an equidigital number, since it uses as much as digits as its factorization.

21801972163 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36288, while the sum is 40.

The spelling of 21801972163 in words is "twenty-one billion, eight hundred one million, nine hundred seventy-two thousand, one hundred sixty-three".