21455152421621 has 2 divisors, whose sum is σ = 21455152421622. Its totient is φ = 21455152421620.

The previous prime is 21455152421617. The next prime is 21455152421693. The reversal of 21455152421621 is 12612425155412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12582528518596 + 8872623903025 = 3547186^2 + 2978695^2 .

It is a cyclic number.

It is not a de Polignac number, because 21455152421621 - 2² = 21455152421617 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21455152421321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10727576210810 + 10727576210811.

It is an arithmetic number, because the mean of its divisors is an integer number (10727576210811).

Almost surely, 2^{21455152421621} is an apocalyptic number.

It is an amenable number.

21455152421621 is a deficient number, since it is larger than the sum of its proper divisors (1).

21455152421621 is an equidigital number, since it uses as much as digits as its factorization.

21455152421621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 192000, while the sum is 41.

The spelling of 21455152421621 in words is "twenty-one trillion, four hundred fifty-five billion, one hundred fifty-two million, four hundred twenty-one thousand, six hundred twenty-one".