21949951 has 2 divisors, whose sum is σ = 21949952. Its totient is φ = 21949950.

The previous prime is 21949927. The next prime is 21949969. The reversal of 21949951 is 15994912.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21949951 - 2¹¹ = 21947903 is a prime.

It is a plaindrome in base 8.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21949051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10974975 + 10974976.

It is an arithmetic number, because the mean of its divisors is an integer number (10974976).

Almost surely, 2^21949951 is an apocalyptic number.

21949951 is a deficient number, since it is larger than the sum of its proper divisors (1).

21949951 is an equidigital number, since it uses as much as digits as its factorization.

21949951 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 29160, while the sum is 40.

The square root of 21949951 is about 4685.0774806827. The cubic root of 21949951 is about 279.9912879942.

The spelling of 21949951 in words is "twenty-one million, nine hundred forty-nine thousand, nine hundred fifty-one".