21378210 has 48 divisors (see below), whose sum is σ = 59688576. Its totient is φ = 4886112.

The previous prime is 21378209. The next prime is 21378223. The reversal of 21378210 is 1287312.

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, 5802 + ... + 8741.

It is an arithmetic number, because the mean of its divisors is an integer number (1243512).

Almost surely, 2^21378210 is an apocalyptic number.

21378210 is an abundant number, since it is smaller than the sum of its proper divisors (38310366).

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

21378210 is a wasteful number, since it uses less digits than its factorization.

21378210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14567 (or 14560 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 24.

The square root of 21378210 is about 4623.6576430354. The cubic root of 21378210 is about 277.5388469275.

The spelling of 21378210 in words is "twenty-one million, three hundred seventy-eight thousand, two hundred ten".