21825040 has 20 divisors (see below), whose sum is σ = 50743404. Its totient is φ = 8729984.

The previous prime is 21825031. The next prime is 21825043. The reversal of 21825040 is 4052812.

It can be written as a sum of positive squares in 2 ways, for example, as 15023376 + 6801664 = 3876^2 + 2608^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is not an unprimeable number, because it can be changed into a prime (21825043) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 136327 + ... + 136486.

Almost surely, 2^21825040 is an apocalyptic number.

21825040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21825040 is an abundant number, since it is smaller than the sum of its proper divisors (28918364).

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

21825040 is a wasteful number, since it uses less digits than its factorization.

21825040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 272826 (or 272820 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 22.

The square root of 21825040 is about 4671.7277317926. The cubic root of 21825040 is about 279.4591600835.

Adding to 21825040 its reverse (4052812), we get a palindrome (25877852).

The spelling of 21825040 in words is "twenty-one million, eight hundred twenty-five thousand, forty".