21717460 has 12 divisors (see below), whose sum is σ = 45606708. Its totient is φ = 8686976.

The previous prime is 21717407. The next prime is 21717461. The reversal of 21717460 is 6471712.

It can be written as a sum of positive squares in 2 ways, for example, as 12194064 + 9523396 = 3492^2 + 3086^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21717461) 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, 542917 + ... + 542956.

It is an arithmetic number, because the mean of its divisors is an integer number (3800559).

Almost surely, 2^21717460 is an apocalyptic number.

21717460 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21717460 is an abundant number, since it is smaller than the sum of its proper divisors (23889248).

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

21717460 is a wasteful number, since it uses less digits than its factorization.

21717460 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1085882 (or 1085880 counting only the distinct ones).

The product of its (nonzero) digits is 2352, while the sum is 28.

The square root of 21717460 is about 4660.1995665422. The cubic root of 21717460 is about 278.9992334781. Note that the first 3 decimals are identical.

The spelling of 21717460 in words is "twenty-one million, seven hundred seventeen thousand, four hundred sixty".