21343643 has 2 divisors, whose sum is σ = 21343644. Its totient is φ = 21343642.

The previous prime is 21343633. The next prime is 21343649. The reversal of 21343643 is 34634312.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21343643 - 2⁶ = 21343579 is a prime.

It is a super-2 number, since 2×21343643² = 911102193022898, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21343649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10671821 + 10671822.

It is an arithmetic number, because the mean of its divisors is an integer number (10671822).

Almost surely, 2^21343643 is an apocalyptic number.

21343643 is a deficient number, since it is larger than the sum of its proper divisors (1).

21343643 is an equidigital number, since it uses as much as digits as its factorization.

21343643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 26.

The square root of 21343643 is about 4619.9180728667. The cubic root of 21343643 is about 277.3891795678.

Adding to 21343643 its reverse (34634312), we get a palindrome (55977955).

The spelling of 21343643 in words is "twenty-one million, three hundred forty-three thousand, six hundred forty-three".