21768768 has 84 divisors (see below), whose sum is σ = 71323200. Its totient is φ = 6218496.

The previous prime is 21768757. The next prime is 21768779. The reversal of 21768768 is 86786712.

It is an interprime number because it is at equal distance from previous prime (21768757) and next prime (21768779).

It is a tau number, because it is divible by the number of its divisors (84).

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

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1333 + ... + 6731.

Almost surely, 2^21768768 is an apocalyptic number.

21768768 is a gapful number since it is divisible by the number (28) 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 21768768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35661600).

21768768 is an abundant number, since it is smaller than the sum of its proper divisors (49554432).

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

21768768 is a wasteful number, since it uses less digits than its factorization.

21768768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5424 (or 5411 counting only the distinct ones).

The product of its digits is 225792, while the sum is 45.

The square root of 21768768 is about 4665.7012334696. The cubic root of 21768768 is about 279.2187747191.

The spelling of 21768768 in words is "twenty-one million, seven hundred sixty-eight thousand, seven hundred sixty-eight".