21101869949 has 2 divisors, whose sum is σ = 21101869950. Its totient is φ = 21101869948.

The previous prime is 21101869937. The next prime is 21101870011. The reversal of 21101869949 is 94996810112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19621005625 + 1480864324 = 140075^2 + 38482^2 .

It is a cyclic number.

It is not a de Polignac number, because 21101869949 - 2¹⁶ = 21101804413 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21101869897 and 21101869906.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21101862949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550934974 + 10550934975.

It is an arithmetic number, because the mean of its divisors is an integer number (10550934975).

Almost surely, 2^21101869949 is an apocalyptic number.

It is an amenable number.

21101869949 is a deficient number, since it is larger than the sum of its proper divisors (1).

21101869949 is an equidigital number, since it uses as much as digits as its factorization.

21101869949 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 279936, while the sum is 50.

The spelling of 21101869949 in words is "twenty-one billion, one hundred one million, eight hundred sixty-nine thousand, nine hundred forty-nine".