21025140 has 48 divisors (see below), whose sum is σ = 59317440. Its totient is φ = 5564160.

The previous prime is 21025129. The next prime is 21025157. The reversal of 21025140 is 4152012.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

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, 7080 + ... + 9600.

It is an arithmetic number, because the mean of its divisors is an integer number (1235780).

Almost surely, 2^21025140 is an apocalyptic number.

21025140 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 21025140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29658720).

21025140 is an abundant number, since it is smaller than the sum of its proper divisors (38292300).

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

21025140 is a wasteful number, since it uses less digits than its factorization.

21025140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2672 (or 2670 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 15.

The square root of 21025140 is about 4585.3178733868. The cubic root of 21025140 is about 276.0024679468.

Adding to 21025140 its reverse (4152012), we get a palindrome (25177152).

The spelling of 21025140 in words is "twenty-one million, twenty-five thousand, one hundred forty".