21621772267129 has 2 divisors, whose sum is σ = 21621772267130. Its totient is φ = 21621772267128.

The previous prime is 21621772267061. The next prime is 21621772267163. The reversal of 21621772267129 is 92176227712612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19651533330025 + 1970238937104 = 4433005^2 + 1403652^2 .

It is a cyclic number.

It is not a de Polignac number, because 21621772267129 - 2¹⁷ = 21621772136057 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21621772267129.

It is not a weakly prime, because it can be changed into another prime (21621772207129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10810886133564 + 10810886133565.

It is an arithmetic number, because the mean of its divisors is an integer number (10810886133565).

Almost surely, 2^{21621772267129} is an apocalyptic number.

It is an amenable number.

21621772267129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21621772267129 is an equidigital number, since it uses as much as digits as its factorization.

21621772267129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3556224, while the sum is 55.

The spelling of 21621772267129 in words is "twenty-one trillion, six hundred twenty-one billion, seven hundred seventy-two million, two hundred sixty-seven thousand, one hundred twenty-nine".