21964243 has 4 divisors (see below), whose sum is σ = 25102000. Its totient is φ = 18826488.

The previous prime is 21964231. The next prime is 21964259. The reversal of 21964243 is 34246912.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21964243 - 2⁹ = 21963731 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21961243) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1568868 + ... + 1568881.

It is an arithmetic number, because the mean of its divisors is an integer number (6275500).

Almost surely, 2^21964243 is an apocalyptic number.

21964243 is a deficient number, since it is larger than the sum of its proper divisors (3137757).

21964243 is an equidigital number, since it uses as much as digits as its factorization.

21964243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3137756.

The product of its digits is 10368, while the sum is 31.

The square root of 21964243 is about 4686.6025007461. The cubic root of 21964243 is about 280.0520438974.

The spelling of 21964243 in words is "twenty-one million, nine hundred sixty-four thousand, two hundred forty-three".