21540412 has 12 divisors (see below), whose sum is σ = 38911936. Its totient is φ = 10422720.

The previous prime is 21540383. The next prime is 21540437. The reversal of 21540412 is 21404512.

It is a self number, because there is not a number n which added to its sum of digits gives 21540412.

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, 86733 + ... + 86980.

Almost surely, 2^21540412 is an apocalyptic number.

It is an amenable number.

21540412 is a deficient number, since it is larger than the sum of its proper divisors (17371524).

21540412 is a wasteful number, since it uses less digits than its factorization.

21540412 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173748 (or 173746 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 19.

The square root of 21540412 is about 4641.1649399693. The cubic root of 21540412 is about 278.2389987920.

Adding to 21540412 its reverse (21404512), we get a palindrome (42944924).

It can be divided in two parts, 21540 and 412, that added together give a cube (21952 = 28³).

The spelling of 21540412 in words is "twenty-one million, five hundred forty thousand, four hundred twelve".