21897560 has 32 divisors (see below), whose sum is σ = 49831200. Its totient is φ = 8659200.

The previous prime is 21897559. The next prime is 21897569. The reversal of 21897560 is 6579812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21897569) 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, 485 + ... + 6635.

It is an arithmetic number, because the mean of its divisors is an integer number (1557225).

Almost surely, 2^21897560 is an apocalyptic number.

21897560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21897560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24915600).

21897560 is an abundant number, since it is smaller than the sum of its proper divisors (27933640).

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

21897560 is a wasteful number, since it uses less digits than its factorization.

21897560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6251 (or 6247 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 38.

The square root of 21897560 is about 4679.4828774128. The cubic root of 21897560 is about 279.7683458119.

The spelling of 21897560 in words is "twenty-one million, eight hundred ninety-seven thousand, five hundred sixty".