21873840 has 40 divisors (see below), whose sum is σ = 67809648. Its totient is φ = 5832960.

The previous prime is 21873833. The next prime is 21873853. The reversal of 21873840 is 4837812.

It is a tau number, because it is divible by the number of its divisors (40).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45331 + ... + 45810.

Almost surely, 2^21873840 is an apocalyptic number.

21873840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21873840 is an abundant number, since it is smaller than the sum of its proper divisors (45935808).

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

21873840 is a wasteful number, since it uses less digits than its factorization.

21873840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91157 (or 91151 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 33.

The square root of 21873840 is about 4676.9477226071. The cubic root of 21873840 is about 279.6672918933.

The spelling of 21873840 in words is "twenty-one million, eight hundred seventy-three thousand, eight hundred forty".