21431149 has 2 divisors, whose sum is σ = 21431150. Its totient is φ = 21431148.

The previous prime is 21431141. The next prime is 21431161. The reversal of 21431149 is 94113412.

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., 16957924 + 4473225 = 4118^2 + 2115^2 .

It is a cyclic number.

It is not a de Polignac number, because 21431149 - 2³ = 21431141 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21431141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10715574 + 10715575.

It is an arithmetic number, because the mean of its divisors is an integer number (10715575).

Almost surely, 2^21431149 is an apocalyptic number.

It is an amenable number.

21431149 is a deficient number, since it is larger than the sum of its proper divisors (1).

21431149 is an equidigital number, since it uses as much as digits as its factorization.

21431149 is an evil number, because the sum of its binary digits is even.

The product of its digits is 864, while the sum is 25.

The square root of 21431149 is about 4629.3789000254. The cubic root of 21431149 is about 277.7677485031.

The spelling of 21431149 in words is "twenty-one million, four hundred thirty-one thousand, one hundred forty-nine".