21964438 has 16 divisors (see below), whose sum is σ = 33907104. Its totient is φ = 10664640.

The previous prime is 21964429. The next prime is 21964451. The reversal of 21964438 is 83446912.

21964438 = 132² + 133² + ... + 408².

It is a junction number, because it is equal to n+sod(n) for n = 21964397 and 21964406.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22231 + ... + 23197.

It is an arithmetic number, because the mean of its divisors is an integer number (2119194).

Almost surely, 2^21964438 is an apocalyptic number.

21964438 is a deficient number, since it is larger than the sum of its proper divisors (11942666).

21964438 is a wasteful number, since it uses less digits than its factorization.

21964438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1287.

The product of its digits is 41472, while the sum is 37.

The square root of 21964438 is about 4686.6233046832. The cubic root of 21964438 is about 280.0528726684.

The spelling of 21964438 in words is "twenty-one million, nine hundred sixty-four thousand, four hundred thirty-eight".