21621275447687 has 2 divisors, whose sum is σ = 21621275447688. Its totient is φ = 21621275447686.

The previous prime is 21621275447617. The next prime is 21621275447693. The reversal of 21621275447687 is 78674457212612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21621275447687 - 2²² = 21621271253383 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21621275447617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10810637723843 + 10810637723844.

It is an arithmetic number, because the mean of its divisors is an integer number (10810637723844).

Almost surely, 2^{21621275447687} is an apocalyptic number.

21621275447687 is a deficient number, since it is larger than the sum of its proper divisors (1).

21621275447687 is an equidigital number, since it uses as much as digits as its factorization.

21621275447687 is an evil number, because the sum of its binary digits is even.

The product of its digits is 63221760, while the sum is 62.

The spelling of 21621275447687 in words is "twenty-one trillion, six hundred twenty-one billion, two hundred seventy-five million, four hundred forty-seven thousand, six hundred eighty-seven".