21579012 has 108 divisors (see below), whose sum is σ = 68406156. Its totient is φ = 5685120.

The previous prime is 21578993. The next prime is 21579017. The reversal of 21579012 is 21097512.

It can be written as a sum of positive squares in 2 ways, for example, as 7918596 + 13660416 = 2814^2 + 3696^2 .

It is a super-2 number, since 2×21579012² = 931307517792288, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21579017) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 22462 + ... + 23402.

Almost surely, 2^21579012 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 21579012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34203078).

21579012 is an abundant number, since it is smaller than the sum of its proper divisors (46827144).

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

21579012 is a wasteful number, since it uses less digits than its factorization.

21579012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 978 (or 966 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 27.

The square root of 21579012 is about 4645.3215173979. The cubic root of 21579012 is about 278.4050992427.

The spelling of 21579012 in words is "twenty-one million, five hundred seventy-nine thousand, twelve".