21221057406539 has 2 divisors, whose sum is σ = 21221057406540. Its totient is φ = 21221057406538.

The previous prime is 21221057406473. The next prime is 21221057406547. The reversal of 21221057406539 is 93560475012212.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21221057406539 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21221057406493 and 21221057406502.

It is not a weakly prime, because it can be changed into another prime (21221057406599) 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, 10610528703269 + 10610528703270.

It is an arithmetic number, because the mean of its divisors is an integer number (10610528703270).

Almost surely, 2^{21221057406539} is an apocalyptic number.

21221057406539 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221057406539 is an equidigital number, since it uses as much as digits as its factorization.

21221057406539 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 907200, while the sum is 47.

The spelling of 21221057406539 in words is "twenty-one trillion, two hundred twenty-one billion, fifty-seven million, four hundred six thousand, five hundred thirty-nine".