21237445 has 8 divisors (see below), whose sum is σ = 26173944. Its totient is φ = 16530624.

The previous prime is 21237431. The next prime is 21237493. The reversal of 21237445 is 54473212.

It can be written as a sum of positive squares in 4 ways, for example, as 1718721 + 19518724 = 1311^2 + 4418^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21237445 - 2⁵ = 21237413 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 57214 + ... + 57583.

It is an arithmetic number, because the mean of its divisors is an integer number (3271743).

Almost surely, 2^21237445 is an apocalyptic number.

It is an amenable number.

21237445 is a deficient number, since it is larger than the sum of its proper divisors (4936499).

21237445 is a wasteful number, since it uses less digits than its factorization.

21237445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114839.

The product of its digits is 6720, while the sum is 28.

The square root of 21237445 is about 4608.4102464950. The cubic root of 21237445 is about 276.9283527505.

The spelling of 21237445 in words is "twenty-one million, two hundred thirty-seven thousand, four hundred forty-five".