21216404165101 has 2 divisors, whose sum is σ = 21216404165102. Its totient is φ = 21216404165100.

The previous prime is 21216404165053. The next prime is 21216404165147. The reversal of 21216404165101 is 10156140461212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16417123758025 + 4799280407076 = 4051805^2 + 2190726^2 .

It is a cyclic number.

It is not a de Polignac number, because 21216404165101 - 2⁷ = 21216404164973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21216404165171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10608202082550 + 10608202082551.

It is an arithmetic number, because the mean of its divisors is an integer number (10608202082551).

Almost surely, 2^{21216404165101} is an apocalyptic number.

It is an amenable number.

21216404165101 is a deficient number, since it is larger than the sum of its proper divisors (1).

21216404165101 is an equidigital number, since it uses as much as digits as its factorization.

21216404165101 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11520, while the sum is 34.

The spelling of 21216404165101 in words is "twenty-one trillion, two hundred sixteen billion, four hundred four million, one hundred sixty-five thousand, one hundred one".