2172305221621 has 2 divisors, whose sum is σ = 2172305221622. Its totient is φ = 2172305221620.

The previous prime is 2172305221609. The next prime is 2172305221637. The reversal of 2172305221621 is 1261225032712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1969840320100 + 202464901521 = 1403510^2 + 449961^2 .

It is a cyclic number.

It is not a de Polignac number, because 2172305221621 - 2⁵ = 2172305221589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2172305221651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1086152610810 + 1086152610811.

It is an arithmetic number, because the mean of its divisors is an integer number (1086152610811).

Almost surely, 2^{2172305221621} is an apocalyptic number.

It is an amenable number.

2172305221621 is a deficient number, since it is larger than the sum of its proper divisors (1).

2172305221621 is an equidigital number, since it uses as much as digits as its factorization.

2172305221621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20160, while the sum is 34.

The spelling of 2172305221621 in words is "two trillion, one hundred seventy-two billion, three hundred five million, two hundred twenty-one thousand, six hundred twenty-one".