21389445 has 48 divisors (see below), whose sum is σ = 46230912. Its totient is φ = 8887680.

The previous prime is 21389437. The next prime is 21389453. The reversal of 21389445 is 54498312.

It is an interprime number because it is at equal distance from previous prime (21389437) and next prime (21389453).

It is not a de Polignac number, because 21389445 - 2³ = 21389437 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 379 + ... + 6551.

It is an arithmetic number, because the mean of its divisors is an integer number (963144).

Almost surely, 2^21389445 is an apocalyptic number.

It is an amenable number.

21389445 is an abundant number, since it is smaller than the sum of its proper divisors (24841467).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21389445 is a wasteful number, since it uses less digits than its factorization.

21389445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6202 (or 6199 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 21389445 is about 4624.8724306731. The cubic root of 21389445 is about 277.5874572161.

The spelling of 21389445 in words is "twenty-one million, three hundred eighty-nine thousand, four hundred forty-five".