21869540 has 72 divisors (see below), whose sum is σ = 57736896. Its totient is φ = 6811200.

The previous prime is 21869521. The next prime is 21869557. The reversal of 21869540 is 4596812.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 21869540.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16295 + ... + 17585.

Almost surely, 2^21869540 is an apocalyptic number.

21869540 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 21869540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28868448).

21869540 is an abundant number, since it is smaller than the sum of its proper divisors (35867356).

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

21869540 is a wasteful number, since it uses less digits than its factorization.

21869540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1329 (or 1316 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 21869540 is about 4676.4879984878. The cubic root of 21869540 is about 279.6489648541.

The spelling of 21869540 in words is "twenty-one million, eight hundred sixty-nine thousand, five hundred forty".