21222997 has 4 divisors (see below), whose sum is σ = 22145760. Its totient is φ = 20300236.

The previous prime is 21222979. The next prime is 21223009. The reversal of 21222997 is 79922212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21222997 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 (21222967) 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, 461347 + ... + 461392.

It is an arithmetic number, because the mean of its divisors is an integer number (5536440).

Almost surely, 2^21222997 is an apocalyptic number.

It is an amenable number.

21222997 is a deficient number, since it is larger than the sum of its proper divisors (922763).

21222997 is an equidigital number, since it uses as much as digits as its factorization.

21222997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 922762.

The product of its digits is 9072, while the sum is 34.

The square root of 21222997 is about 4606.8424110230. The cubic root of 21222997 is about 276.8655396625.

The spelling of 21222997 in words is "twenty-one million, two hundred twenty-two thousand, nine hundred ninety-seven".