21515454163309 has 2 divisors, whose sum is σ = 21515454163310. Its totient is φ = 21515454163308.

The previous prime is 21515454163289. The next prime is 21515454163337. The reversal of 21515454163309 is 90336145451512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17358239007684 + 4157215155625 = 4166322^2 + 2038925^2 .

It is a cyclic number.

It is not a de Polignac number, because 21515454163309 - 2¹¹ = 21515454161261 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21515454163009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10757727081654 + 10757727081655.

It is an arithmetic number, because the mean of its divisors is an integer number (10757727081655).

Almost surely, 2^{21515454163309} is an apocalyptic number.

It is an amenable number.

21515454163309 is a deficient number, since it is larger than the sum of its proper divisors (1).

21515454163309 is an equidigital number, since it uses as much as digits as its factorization.

21515454163309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1944000, while the sum is 49.

The spelling of 21515454163309 in words is "twenty-one trillion, five hundred fifteen billion, four hundred fifty-four million, one hundred sixty-three thousand, three hundred nine".