21346621 has 2 divisors, whose sum is σ = 21346622. Its totient is φ = 21346620.

The previous prime is 21346573. The next prime is 21346627. The reversal of 21346621 is 12664312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19483396 + 1863225 = 4414^2 + 1365^2 .

It is a cyclic number.

It is not a de Polignac number, because 21346621 - 2⁹ = 21346109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21346627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10673310 + 10673311.

It is an arithmetic number, because the mean of its divisors is an integer number (10673311).

Almost surely, 2^21346621 is an apocalyptic number.

It is an amenable number.

21346621 is a deficient number, since it is larger than the sum of its proper divisors (1).

21346621 is an equidigital number, since it uses as much as digits as its factorization.

21346621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1728, while the sum is 25.

The square root of 21346621 is about 4620.2403617128. The cubic root of 21346621 is about 277.4020799985.

The spelling of 21346621 in words is "twenty-one million, three hundred forty-six thousand, six hundred twenty-one".