21524140 has 48 divisors (see below), whose sum is σ = 49641984. Its totient is φ = 7774400.

The previous prime is 21524117. The next prime is 21524171. The reversal of 21524140 is 4142512.

It is a zygodrome in base 9.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49725 + ... + 50155.

It is an arithmetic number, because the mean of its divisors is an integer number (1034208).

Almost surely, 2^21524140 is an apocalyptic number.

21524140 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 21524140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24820992).

21524140 is an abundant number, since it is smaller than the sum of its proper divisors (28117844).

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

21524140 is a wasteful number, since it uses less digits than its factorization.

21524140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 678 (or 676 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 19.

The square root of 21524140 is about 4639.4116006235. The cubic root of 21524140 is about 278.1689189575.

Adding to 21524140 its reverse (4142512), we get a palindrome (25666652).

The spelling of 21524140 in words is "twenty-one million, five hundred twenty-four thousand, one hundred forty".