21237149 has 4 divisors (see below), whose sum is σ = 21811164. Its totient is φ = 20663136.

The previous prime is 21237143. The next prime is 21237157. The reversal of 21237149 is 94173212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12652249 + 8584900 = 3557^2 + 2930^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21237149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21237143) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 286952 + ... + 287025.

It is an arithmetic number, because the mean of its divisors is an integer number (5452791).

Almost surely, 2^21237149 is an apocalyptic number.

It is an amenable number.

21237149 is a deficient number, since it is larger than the sum of its proper divisors (574015).

21237149 is an equidigital number, since it uses as much as digits as its factorization.

21237149 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 574014.

The product of its digits is 3024, while the sum is 29.

The square root of 21237149 is about 4608.3781311867. The cubic root of 21237149 is about 276.9270661680.

The spelling of 21237149 in words is "twenty-one million, two hundred thirty-seven thousand, one hundred forty-nine".