21231939 has 4 divisors (see below), whose sum is σ = 28309256. Its totient is φ = 14154624.

The previous prime is 21231937. The next prime is 21231941. The reversal of 21231939 is 93913212.

It is a happy number.

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

It is an interprime number because it is at equal distance from previous prime (21231937) and next prime (21231941).

It is not a de Polignac number, because 21231939 - 2¹ = 21231937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21231937) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3538654 + ... + 3538659.

It is an arithmetic number, because the mean of its divisors is an integer number (7077314).

Almost surely, 2^21231939 is an apocalyptic number.

21231939 is a deficient number, since it is larger than the sum of its proper divisors (7077317).

21231939 is an equidigital number, since it uses as much as digits as its factorization.

21231939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7077316.

The product of its digits is 2916, while the sum is 30.

The square root of 21231939 is about 4607.8128217192. The cubic root of 21231939 is about 276.9044186206.

The spelling of 21231939 in words is "twenty-one million, two hundred thirty-one thousand, nine hundred thirty-nine".