21842840 has 16 divisors (see below), whose sum is σ = 49146480. Its totient is φ = 8737120.

The previous prime is 21842813. The next prime is 21842851. The reversal of 21842840 is 4824812.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 272996 + ... + 273075.

It is an arithmetic number, because the mean of its divisors is an integer number (3071655).

Almost surely, 2^21842840 is an apocalyptic number.

21842840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21842840 is an abundant number, since it is smaller than the sum of its proper divisors (27303640).

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

21842840 is a wasteful number, since it uses less digits than its factorization.

21842840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 546082 (or 546078 counting only the distinct ones).

The product of its (nonzero) digits is 4096, while the sum is 29.

The square root of 21842840 is about 4673.6324202915. The cubic root of 21842840 is about 279.5351129238.

The spelling of 21842840 in words is "twenty-one million, eight hundred forty-two thousand, eight hundred forty".