21219937 has 2 divisors, whose sum is σ = 21219938. Its totient is φ = 21219936.

The previous prime is 21219929. The next prime is 21219949. The reversal of 21219937 is 73991212.

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., 21123216 + 96721 = 4596^2 + 311^2 .

It is a cyclic number.

It is not a de Polignac number, because 21219937 - 2³ = 21219929 is a prime.

It is not a weakly prime, because it can be changed into another prime (21219917) 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 as a sum of consecutive naturals, namely, 10609968 + 10609969.

It is an arithmetic number, because the mean of its divisors is an integer number (10609969).

Almost surely, 2^21219937 is an apocalyptic number.

It is an amenable number.

21219937 is a deficient number, since it is larger than the sum of its proper divisors (1).

21219937 is an equidigital number, since it uses as much as digits as its factorization.

21219937 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6804, while the sum is 34.

The square root of 21219937 is about 4606.5102843693. The cubic root of 21219937 is about 276.8522325681.

The spelling of 21219937 in words is "twenty-one million, two hundred nineteen thousand, nine hundred thirty-seven".