21559440 has 160 divisors (see below), whose sum is σ = 78494976. Its totient is φ = 4792320.

The previous prime is 21559429. The next prime is 21559463. The reversal of 21559440 is 4495512.

It is a super-2 number, since 2×21559440² = 929618906227200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21559398 and 21559407.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 68724 + ... + 69036.

Almost surely, 2^21559440 is an apocalyptic number.

21559440 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 21559440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39247488).

21559440 is an abundant number, since it is smaller than the sum of its proper divisors (56935536).

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

21559440 is a wasteful number, since it uses less digits than its factorization.

21559440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 377 (or 371 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 21559440 is about 4643.2144038371. The cubic root of 21559440 is about 278.3209033457.

The spelling of 21559440 in words is "twenty-one million, five hundred fifty-nine thousand, four hundred forty".