21213149 has 2 divisors, whose sum is σ = 21213150. Its totient is φ = 21213148.

The previous prime is 21213119. The next prime is 21213163. The reversal of 21213149 is 94131212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20748025 + 465124 = 4555^2 + 682^2 .

It is a cyclic number.

It is not a de Polignac number, because 21213149 - 2²⁴ = 4435933 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21213109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606574 + 10606575.

It is an arithmetic number, because the mean of its divisors is an integer number (10606575).

Almost surely, 2^21213149 is an apocalyptic number.

It is an amenable number.

21213149 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213149 is an equidigital number, since it uses as much as digits as its factorization.

21213149 is an evil number, because the sum of its binary digits is even.

The product of its digits is 432, while the sum is 23.

The square root of 21213149 is about 4605.7734421050. The cubic root of 21213149 is about 276.8227088648.

The spelling of 21213149 in words is "twenty-one million, two hundred thirteen thousand, one hundred forty-nine".