21411840 has 192 divisors, whose sum is σ = 74299680. Its totient is φ = 5242880.

The previous prime is 21411839. The next prime is 21411847. The reversal of 21411840 is 4811412.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (192).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21411847) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 522220 + ... + 522260.

Almost surely, 2^21411840 is an apocalyptic number.

21411840 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 21411840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37149840).

21411840 is an abundant number, since it is smaller than the sum of its proper divisors (52887840).

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

21411840 is a wasteful number, since it uses less digits than its factorization.

21411840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88 (or 68 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 21.

The square root of 21411840 is about 4627.2929451246. The cubic root of 21411840 is about 277.6843025333.

The spelling of 21411840 in words is "twenty-one million, four hundred eleven thousand, eight hundred forty".