21345164549 has 2 divisors, whose sum is σ = 21345164550. Its totient is φ = 21345164548.

The previous prime is 21345164443. The next prime is 21345164567. The reversal of 21345164549 is 94546154312.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17441164225 + 3904000324 = 132065^2 + 62482^2 .

It is a cyclic number.

It is not a de Polignac number, because 21345164549 - 2⁸ = 21345164293 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21345164569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10672582274 + 10672582275.

It is an arithmetic number, because the mean of its divisors is an integer number (10672582275).

Almost surely, 2^21345164549 is an apocalyptic number.

It is an amenable number.

21345164549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21345164549 is an equidigital number, since it uses as much as digits as its factorization.

21345164549 is an evil number, because the sum of its binary digits is even.

The product of its digits is 518400, while the sum is 44.

The spelling of 21345164549 in words is "twenty-one billion, three hundred forty-five million, one hundred sixty-four thousand, five hundred forty-nine".