21670012 has 48 divisors (see below), whose sum is σ = 47965120. Its totient is φ = 8335872.

The previous prime is 21670009. The next prime is 21670031. The reversal of 21670012 is 21007612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12664 + ... + 14272.

Almost surely, 2^21670012 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 21670012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23982560).

21670012 is an abundant number, since it is smaller than the sum of its proper divisors (26295108).

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

21670012 is a wasteful number, since it uses less digits than its factorization.

21670012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1670 (or 1668 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 21670012 is about 4655.1060138304. The cubic root of 21670012 is about 278.7959007979.

Adding to 21670012 its reverse (21007612), we get a palindrome (42677624).

The spelling of 21670012 in words is "twenty-one million, six hundred seventy thousand, twelve".