21573136 has 40 divisors (see below), whose sum is σ = 47668824. Its totient is φ = 9369600.

The previous prime is 21573131. The next prime is 21573163. The reversal of 21573136 is 63137512.

It can be written as a sum of positive squares in 4 ways, for example, as 3459600 + 18113536 = 1860^2 + 4256^2 .

It is a Smith number, since the sum of its digits (28) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21573131) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 486 + ... + 6586.

Almost surely, 2^21573136 is an apocalyptic number.

21573136 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21573136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23834412).

21573136 is an abundant number, since it is smaller than the sum of its proper divisors (26095688).

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

21573136 is a wasteful number, since it uses less digits than its factorization.

21573136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6139 (or 6133 counting only the distinct ones).

The product of its digits is 3780, while the sum is 28.

The square root of 21573136 is about 4644.6890100415. The cubic root of 21573136 is about 278.3798268952.

The spelling of 21573136 in words is "twenty-one million, five hundred seventy-three thousand, one hundred thirty-six".