21299669 has 2 divisors, whose sum is σ = 21299670. Its totient is φ = 21299668.

The previous prime is 21299647. The next prime is 21299687. The reversal of 21299669 is 96699212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21298225 + 1444 = 4615^2 + 38^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21299669 is a prime.

It is a super-2 number, since 2×21299669² = 907351799019122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21299639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10649834 + 10649835.

It is an arithmetic number, because the mean of its divisors is an integer number (10649835).

Almost surely, 2^21299669 is an apocalyptic number.

It is an amenable number.

21299669 is a deficient number, since it is larger than the sum of its proper divisors (1).

21299669 is an equidigital number, since it uses as much as digits as its factorization.

21299669 is an evil number, because the sum of its binary digits is even.

The product of its digits is 104976, while the sum is 44.

The square root of 21299669 is about 4615.1564437189. The cubic root of 21299669 is about 277.1985482802.

The spelling of 21299669 in words is "twenty-one million, two hundred ninety-nine thousand, six hundred sixty-nine".