21570012 has 36 divisors (see below), whose sum is σ = 54827136. Its totient is φ = 7150080.

The previous prime is 21570011. The next prime is 21570019. The reversal of 21570012 is 21007512.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21570011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5308 + ... + 8444.

It is an arithmetic number, because the mean of its divisors is an integer number (1522976).

Almost surely, 2^21570012 is an apocalyptic number.

It is an amenable number.

21570012 is an abundant number, since it is smaller than the sum of its proper divisors (33257124).

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

21570012 is a wasteful number, since it uses less digits than its factorization.

21570012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3338 (or 3333 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 21570012 is about 4644.3526997850. The cubic root of 21570012 is about 278.3663888773.

Adding to 21570012 its reverse (21007512), we get a palindrome (42577524).

Subtracting from 21570012 its reverse (21007512), we obtain a square (562500 = 750²).

The spelling of 21570012 in words is "twenty-one million, five hundred seventy thousand, twelve".