21621772266989 has 2 divisors, whose sum is σ = 21621772266990. Its totient is φ = 21621772266988.

The previous prime is 21621772266973. The next prime is 21621772267009. The reversal of 21621772266989 is 98966227712612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19726078374025 + 1895693892964 = 4441405^2 + 1376842^2 .

It is a cyclic number.

It is not a de Polignac number, because 21621772266989 - 2⁴ = 21621772266973 is a prime.

It is a super-2 number, since 2×21621772266989² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21621772266389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10810886133494 + 10810886133495.

It is an arithmetic number, because the mean of its divisors is an integer number (10810886133495).

Almost surely, 2^{21621772266989} is an apocalyptic number.

It is an amenable number.

21621772266989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21621772266989 is an equidigital number, since it uses as much as digits as its factorization.

21621772266989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 109734912, while the sum is 68.

The spelling of 21621772266989 in words is "twenty-one trillion, six hundred twenty-one billion, seven hundred seventy-two million, two hundred sixty-six thousand, nine hundred eighty-nine".