21399526329449 has 2 divisors, whose sum is σ = 21399526329450. Its totient is φ = 21399526329448.

The previous prime is 21399526329421. The next prime is 21399526329523. The reversal of 21399526329449 is 94492362599312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21399478165849 + 48163600 = 4625957^2 + 6940^2 .

It is a cyclic number.

It is not a de Polignac number, because 21399526329449 - 2²⁴ = 21399509552233 is a prime.

It is not a weakly prime, because it can be changed into another prime (21399526329149) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10699763164724 + 10699763164725.

It is an arithmetic number, because the mean of its divisors is an integer number (10699763164725).

Almost surely, 2^{21399526329449} is an apocalyptic number.

It is an amenable number.

21399526329449 is a deficient number, since it is larger than the sum of its proper divisors (1).

21399526329449 is an equidigital number, since it uses as much as digits as its factorization.

21399526329449 is an evil number, because the sum of its binary digits is even.

The product of its digits is 226748160, while the sum is 68.

The spelling of 21399526329449 in words is "twenty-one trillion, three hundred ninety-nine billion, five hundred twenty-six million, three hundred twenty-nine thousand, four hundred forty-nine".