21442840 has 32 divisors (see below), whose sum is σ = 48378960. Its totient is φ = 8553600.

The previous prime is 21442819. The next prime is 21442871. The reversal of 21442840 is 4824412.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26035 + ... + 26845.

Almost surely, 2^21442840 is an apocalyptic number.

21442840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21442840 is an abundant number, since it is smaller than the sum of its proper divisors (26936120).

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

21442840 is a wasteful number, since it uses less digits than its factorization.

21442840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1483 (or 1479 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 25.

The square root of 21442840 is about 4630.6414242522. The cubic root of 21442840 is about 277.8182480887.

The spelling of 21442840 in words is "twenty-one million, four hundred forty-two thousand, eight hundred forty".