21678450 has 48 divisors (see below), whose sum is σ = 55029216. Its totient is φ = 5644800.

The previous prime is 21678439. The next prime is 21678479. The reversal of 21678450 is 5487612.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4770 + ... + 8130.

It is an arithmetic number, because the mean of its divisors is an integer number (1146442).

Almost surely, 2^21678450 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21678450, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27514608).

21678450 is an abundant number, since it is smaller than the sum of its proper divisors (33350766).

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

21678450 is a wasteful number, since it uses less digits than its factorization.

21678450 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3419 (or 3414 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 21678450 is about 4656.0122422519. The cubic root of 21678450 is about 278.8320825120.

The spelling of 21678450 in words is "twenty-one million, six hundred seventy-eight thousand, four hundred fifty".