21868404949 has 2 divisors, whose sum is σ = 21868404950. Its totient is φ = 21868404948.

The previous prime is 21868404931. The next prime is 21868404979. The reversal of 21868404949 is 94940486812.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20012346225 + 1856058724 = 141465^2 + 43082^2 .

It is a cyclic number.

It is not a de Polignac number, because 21868404949 - 2²³ = 21860016341 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21868404949.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21868404919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10934202474 + 10934202475.

It is an arithmetic number, because the mean of its divisors is an integer number (10934202475).

Almost surely, 2^21868404949 is an apocalyptic number.

It is an amenable number.

21868404949 is a deficient number, since it is larger than the sum of its proper divisors (1).

21868404949 is an equidigital number, since it uses as much as digits as its factorization.

21868404949 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3981312, while the sum is 55.

The spelling of 21868404949 in words is "twenty-one billion, eight hundred sixty-eight million, four hundred four thousand, nine hundred forty-nine".