21620369 has 2 divisors, whose sum is σ = 21620370. Its totient is φ = 21620368.

The previous prime is 21620359. The next prime is 21620383. The reversal of 21620369 is 96302612.

21620369 is nontrivially palindromic in base 8.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13140625 + 8479744 = 3625^2 + 2912^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21620369 is a prime.

It is a super-2 number, since 2×21620369² = 934880711392322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21620359) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10810184 + 10810185.

It is an arithmetic number, because the mean of its divisors is an integer number (10810185).

Almost surely, 2^21620369 is an apocalyptic number.

It is an amenable number.

21620369 is a deficient number, since it is larger than the sum of its proper divisors (1).

21620369 is an equidigital number, since it uses as much as digits as its factorization.

21620369 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3888, while the sum is 29.

The square root of 21620369 is about 4649.7708545691. The cubic root of 21620369 is about 278.5828437387.

The spelling of 21620369 in words is "twenty-one million, six hundred twenty thousand, three hundred sixty-nine".