21869149 has 2 divisors, whose sum is σ = 21869150. Its totient is φ = 21869148.

The previous prime is 21869137. The next prime is 21869153. The reversal of 21869149 is 94196812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11902500 + 9966649 = 3450^2 + 3157^2 .

It is a cyclic number.

It is not a de Polignac number, because 21869149 - 2¹¹ = 21867101 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21869119) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10934574 + 10934575.

It is an arithmetic number, because the mean of its divisors is an integer number (10934575).

Almost surely, 2^21869149 is an apocalyptic number.

It is an amenable number.

21869149 is a deficient number, since it is larger than the sum of its proper divisors (1).

21869149 is an equidigital number, since it uses as much as digits as its factorization.

21869149 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 40.

The square root of 21869149 is about 4676.4461934251. The cubic root of 21869149 is about 279.6472982530.

The spelling of 21869149 in words is "twenty-one million, eight hundred sixty-nine thousand, one hundred forty-nine".