21722609 has 2 divisors, whose sum is σ = 21722610. Its totient is φ = 21722608.

The previous prime is 21722587. The next prime is 21722627. The reversal of 21722609 is 90622712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19114384 + 2608225 = 4372^2 + 1615^2 .

It is a cyclic number.

It is not a de Polignac number, because 21722609 - 2¹² = 21718513 is a prime.

It is not a weakly prime, because it can be changed into another prime (21722629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10861304 + 10861305.

It is an arithmetic number, because the mean of its divisors is an integer number (10861305).

Almost surely, 2^21722609 is an apocalyptic number.

It is an amenable number.

21722609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21722609 is an equidigital number, since it uses as much as digits as its factorization.

21722609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3024, while the sum is 29.

The square root of 21722609 is about 4660.7519779538. The cubic root of 21722609 is about 279.0212810769.

The spelling of 21722609 in words is "twenty-one million, seven hundred twenty-two thousand, six hundred nine".