21755412 has 72 divisors (see below), whose sum is σ = 65627520. Its totient is φ = 6214320.

The previous prime is 21755411. The next prime is 21755413. The reversal of 21755412 is 21455712.

It is an interprime number because it is at equal distance from previous prime (21755411) and next prime (21755413).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21755411) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 3237 + ... + 7347.

Almost surely, 2^21755412 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21755412, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32813760).

21755412 is an abundant number, since it is smaller than the sum of its proper divisors (43872108).

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

21755412 is a wasteful number, since it uses less digits than its factorization.

21755412 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4138 (or 4123 counting only the distinct ones).

The product of its digits is 2800, while the sum is 27.

The square root of 21755412 is about 4664.2697177586. The cubic root of 21755412 is about 279.1616591166.

The spelling of 21755412 in words is "twenty-one million, seven hundred fifty-five thousand, four hundred twelve".