21465221 has 2 divisors, whose sum is σ = 21465222. Its totient is φ = 21465220.

The previous prime is 21465209. The next prime is 21465239. The reversal of 21465221 is 12256412.

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., 14250625 + 7214596 = 3775^2 + 2686^2 .

It is a cyclic number.

It is not a de Polignac number, because 21465221 - 2²² = 17270917 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21465251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10732610 + 10732611.

It is an arithmetic number, because the mean of its divisors is an integer number (10732611).

Almost surely, 2^21465221 is an apocalyptic number.

It is an amenable number.

21465221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21465221 is an equidigital number, since it uses as much as digits as its factorization.

21465221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 960, while the sum is 23.

The square root of 21465221 is about 4633.0574138467. The cubic root of 21465221 is about 277.9148722325.

The spelling of 21465221 in words is "twenty-one million, four hundred sixty-five thousand, two hundred twenty-one".