21015396 has 48 divisors (see below), whose sum is σ = 56250880. Its totient is φ = 6778080.

The previous prime is 21015391. The next prime is 21015403. The reversal of 21015396 is 69351012.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21015391) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 210 + ... + 6486.

Almost surely, 2^21015396 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 21015396, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28125440).

21015396 is an abundant number, since it is smaller than the sum of its proper divisors (35235484).

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

21015396 is a wasteful number, since it uses less digits than its factorization.

21015396 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6321 (or 6313 counting only the distinct ones).

The product of its (nonzero) digits is 1620, while the sum is 27.

The square root of 21015396 is about 4584.2552284968. The cubic root of 21015396 is about 275.9598240197.

The spelling of 21015396 in words is "twenty-one million, fifteen thousand, three hundred ninety-six".