21149951 has 2 divisors, whose sum is σ = 21149952. Its totient is φ = 21149950.

The previous prime is 21149927. The next prime is 21149969. The reversal of 21149951 is 15994112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21149951 - 2¹⁰ = 21148927 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21149911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10574975 + 10574976.

It is an arithmetic number, because the mean of its divisors is an integer number (10574976).

Almost surely, 2^21149951 is an apocalyptic number.

21149951 is a deficient number, since it is larger than the sum of its proper divisors (1).

21149951 is an equidigital number, since it uses as much as digits as its factorization.

21149951 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3240, while the sum is 32.

The square root of 21149951 is about 4598.9075876778. The cubic root of 21149951 is about 276.5475329404.

The spelling of 21149951 in words is "twenty-one million, one hundred forty-nine thousand, nine hundred fifty-one".