21750646849 has 2 divisors, whose sum is σ = 21750646850. Its totient is φ = 21750646848.

The previous prime is 21750646843. The next prime is 21750646861. The reversal of 21750646849 is 94864605712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21482178624 + 268468225 = 146568^2 + 16385^2 .

It is a cyclic number.

It is not a de Polignac number, because 21750646849 - 2³¹ = 19603163201 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21750646796 and 21750646805.

It is not a weakly prime, because it can be changed into another prime (21750646843) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10875323424 + 10875323425.

It is an arithmetic number, because the mean of its divisors is an integer number (10875323425).

Almost surely, 2^21750646849 is an apocalyptic number.

It is an amenable number.

21750646849 is a deficient number, since it is larger than the sum of its proper divisors (1).

21750646849 is an equidigital number, since it uses as much as digits as its factorization.

21750646849 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2903040, while the sum is 52.

The spelling of 21750646849 in words is "twenty-one billion, seven hundred fifty million, six hundred forty-six thousand, eight hundred forty-nine".