21954643 has 2 divisors, whose sum is σ = 21954644. Its totient is φ = 21954642.

The previous prime is 21954631. The next prime is 21954679. The reversal of 21954643 is 34645912.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21954643 - 2²¹ = 19857491 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21954599 and 21954608.

It is not a weakly prime, because it can be changed into another prime (21954613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10977321 + 10977322.

It is an arithmetic number, because the mean of its divisors is an integer number (10977322).

Almost surely, 2^21954643 is an apocalyptic number.

21954643 is a deficient number, since it is larger than the sum of its proper divisors (1).

21954643 is an equidigital number, since it uses as much as digits as its factorization.

21954643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 34.

The square root of 21954643 is about 4685.5781927101. The cubic root of 21954643 is about 280.0112367939.

The spelling of 21954643 in words is "twenty-one million, nine hundred fifty-four thousand, six hundred forty-three".