21378672 has 120 divisors (see below), whose sum is σ = 69328896. Its totient is φ = 6023808.

The previous prime is 21378659. The next prime is 21378683. The reversal of 21378672 is 27687312.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 127933 + ... + 128099.

Almost surely, 2^21378672 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 21378672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34664448).

21378672 is an abundant number, since it is smaller than the sum of its proper divisors (47950224).

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

21378672 is a wasteful number, since it uses less digits than its factorization.

21378672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 315 (or 306 counting only the distinct ones).

The product of its digits is 28224, while the sum is 36.

The square root of 21378672 is about 4623.7076032120. The cubic root of 21378672 is about 277.5408461910.

The spelling of 21378672 in words is "twenty-one million, three hundred seventy-eight thousand, six hundred seventy-two".