21153143549 has 2 divisors, whose sum is σ = 21153143550. Its totient is φ = 21153143548.

The previous prime is 21153143527. The next prime is 21153143567. The reversal of 21153143549 is 94534135112.

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., 12889060900 + 8264082649 = 113530^2 + 90907^2 .

It is a cyclic number.

It is not a de Polignac number, because 21153143549 - 2¹² = 21153139453 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21153143519) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10576571774 + 10576571775.

It is an arithmetic number, because the mean of its divisors is an integer number (10576571775).

Almost surely, 2^21153143549 is an apocalyptic number.

It is an amenable number.

21153143549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21153143549 is an equidigital number, since it uses as much as digits as its factorization.

21153143549 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64800, while the sum is 38.

The spelling of 21153143549 in words is "twenty-one billion, one hundred fifty-three million, one hundred forty-three thousand, five hundred forty-nine".