21678030 has 96 divisors (see below), whose sum is σ = 63842688. Its totient is φ = 5248800.

The previous prime is 21678001. The next prime is 21678037. The reversal of 21678030 is 3087612.

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

It is a junction number, because it is equal to n+sod(n) for n = 21677985 and 21678003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21678037) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 26325 + ... + 27135.

It is an arithmetic number, because the mean of its divisors is an integer number (665028).

Almost surely, 2^21678030 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21678030, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31921344).

21678030 is an abundant number, since it is smaller than the sum of its proper divisors (42164658).

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

21678030 is a wasteful number, since it uses less digits than its factorization.

21678030 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 844 (or 832 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21678030 is about 4655.9671390593. The cubic root of 21678030 is about 278.8302817954.

The spelling of 21678030 in words is "twenty-one million, six hundred seventy-eight thousand, thirty".