21845040 has 80 divisors (see below), whose sum is σ = 77399808. Its totient is φ = 4992768.

The previous prime is 21845029. The next prime is 21845069. The reversal of 21845040 is 4054812.

It is a tau number, because it is divible by the number of its divisors (80).

It is a hoax number, since the sum of its digits (24) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21845040.

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, 4822 + ... + 8181.

Almost surely, 2^21845040 is an apocalyptic number.

21845040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21845040 is an abundant number, since it is smaller than the sum of its proper divisors (55554768).

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

21845040 is a wasteful number, since it uses less digits than its factorization.

21845040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13026 (or 13020 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 24.

The square root of 21845040 is about 4673.8677773339. The cubic root of 21845040 is about 279.5444974880.

Adding to 21845040 its reverse (4054812), we get a palindrome (25899852).

The spelling of 21845040 in words is "twenty-one million, eight hundred forty-five thousand, forty".