21635702849 has 2 divisors, whose sum is σ = 21635702850. Its totient is φ = 21635702848.

The previous prime is 21635702827. The next prime is 21635702867. The reversal of 21635702849 is 94820753612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19325170225 + 2310532624 = 139015^2 + 48068^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21635702849 is a prime.

It is a weakly prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10817851424 + 10817851425.

It is an arithmetic number, because the mean of its divisors is an integer number (10817851425).

It is a 2-persistent number, because it is pandigital, and so is 2⋅21635702849 = 43271405698, but 3⋅21635702849 = 64907108547 is not.

Almost surely, 2^21635702849 is an apocalyptic number.

It is an amenable number.

21635702849 is a deficient number, since it is larger than the sum of its proper divisors (1).

21635702849 is an equidigital number, since it uses as much as digits as its factorization.

21635702849 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 725760, while the sum is 47.

The spelling of 21635702849 in words is "twenty-one billion, six hundred thirty-five million, seven hundred two thousand, eight hundred forty-nine".