21768432 has 160 divisors (see below), whose sum is σ = 70566912. Its totient is φ = 5640192.

The previous prime is 21768431. The next prime is 21768457. The reversal of 21768432 is 23486712.

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21768393 and 21768402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21768431) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 211293 + ... + 211395.

Almost surely, 2^21768432 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 21768432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35283456).

21768432 is an abundant number, since it is smaller than the sum of its proper divisors (48798480).

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

21768432 is a wasteful number, since it uses less digits than its factorization.

21768432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 175 (or 169 counting only the distinct ones).

The product of its digits is 16128, while the sum is 33.

The square root of 21768432 is about 4665.6652258815. The cubic root of 21768432 is about 279.2173381351.

The spelling of 21768432 in words is "twenty-one million, seven hundred sixty-eight thousand, four hundred thirty-two".