21747012 has 96 divisors (see below), whose sum is σ = 62431488. Its totient is φ = 5750784.

The previous prime is 21747007. The next prime is 21747023. The reversal of 21747012 is 21074712.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 138438 + ... + 138594.

It is an arithmetic number, because the mean of its divisors is an integer number (650328).

Almost surely, 2^21747012 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 21747012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31215744).

21747012 is an abundant number, since it is smaller than the sum of its proper divisors (40684476).

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

21747012 is a wasteful number, since it uses less digits than its factorization.

21747012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 285 (or 283 counting only the distinct ones).

The product of its (nonzero) digits is 784, while the sum is 24.

The square root of 21747012 is about 4663.3691683160. The cubic root of 21747012 is about 279.1257253789.

The spelling of 21747012 in words is "twenty-one million, seven hundred forty-seven thousand, twelve".