21258536 has 32 divisors (see below), whose sum is σ = 43545600. Its totient is φ = 9670080.

The previous prime is 21258527. The next prime is 21258539. The reversal of 21258536 is 63585212.

It is not an unprimeable number, because it can be changed into a prime (21258539) 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, 5945 + ... + 8823.

It is an arithmetic number, because the mean of its divisors is an integer number (1360800).

Almost surely, 2^21258536 is an apocalyptic number.

21258536 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 21258536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21772800).

21258536 is an abundant number, since it is smaller than the sum of its proper divisors (22287064).

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

21258536 is a wasteful number, since it uses less digits than its factorization.

21258536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2969 (or 2965 counting only the distinct ones).

The product of its digits is 14400, while the sum is 32.

The square root of 21258536 is about 4610.6979948810. The cubic root of 21258536 is about 277.0199953418.

The spelling of 21258536 in words is "twenty-one million, two hundred fifty-eight thousand, five hundred thirty-six".