21741840 has 60 divisors (see below), whose sum is σ = 73018764. Its totient is φ = 5797632.

The previous prime is 21741823. The next prime is 21741847. The reversal of 21741840 is 4814712.

It can be written as a sum of positive squares in 2 ways, for example, as 6718464 + 15023376 = 2592^2 + 3876^2 .

It is a tau number, because it is divible by the number of its divisors (60).

It is not an unprimeable number, because it can be changed into a prime (21741847) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14379 + ... + 15818.

Almost surely, 2^21741840 is an apocalyptic number.

21741840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21741840 is an abundant number, since it is smaller than the sum of its proper divisors (51276924).

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

21741840 is a wasteful number, since it uses less digits than its factorization.

21741840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30216 (or 30207 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 27.

The square root of 21741840 is about 4662.8146006463. The cubic root of 21741840 is about 279.1035958604.

The spelling of 21741840 in words is "twenty-one million, seven hundred forty-one thousand, eight hundred forty".