21867240 has 64 divisors (see below), whose sum is σ = 66096000. Its totient is φ = 5787392.

The previous prime is 21867221. The next prime is 21867277. The reversal of 21867240 is 4276812.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21867198 and 21867207.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17269 + ... + 18491.

It is an arithmetic number, because the mean of its divisors is an integer number (1032750).

Almost surely, 2^21867240 is an apocalyptic number.

21867240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21867240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33048000).

21867240 is an abundant number, since it is smaller than the sum of its proper divisors (44228760).

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

21867240 is a wasteful number, since it uses less digits than its factorization.

21867240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1386 (or 1382 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 30.

The square root of 21867240 is about 4676.2420809877. The cubic root of 21867240 is about 279.6391610331.

The spelling of 21867240 in words is "twenty-one million, eight hundred sixty-seven thousand, two hundred forty".