21706244 has 24 divisors (see below), whose sum is σ = 43662528. Its totient is φ = 9249120.

The previous prime is 21706241. The next prime is 21706253. The reversal of 21706244 is 44260712.

It is a super-2 number, since 2×21706244² = 942322057175072, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21706241) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2927 + ... + 7209.

It is an arithmetic number, because the mean of its divisors is an integer number (1819272).

Almost surely, 2^21706244 is an apocalyptic number.

It is an amenable number.

21706244 is an abundant number, since it is smaller than the sum of its proper divisors (21956284).

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

21706244 is a wasteful number, since it uses less digits than its factorization.

21706244 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4475 (or 4473 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 26.

The square root of 21706244 is about 4658.9960291891. The cubic root of 21706244 is about 278.9511954132.

Adding to 21706244 its reverse (44260712), we get a palindrome (65966956).

The spelling of 21706244 in words is "twenty-one million, seven hundred six thousand, two hundred forty-four".