21015036 has 72 divisors (see below), whose sum is σ = 61457760. Its totient is φ = 5930496.

The previous prime is 21015023. The next prime is 21015041. The reversal of 21015036 is 63051012.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21960 + ... + 22896.

It is an arithmetic number, because the mean of its divisors is an integer number (853580).

Almost surely, 2^21015036 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 21015036, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30728880).

21015036 is an abundant number, since it is smaller than the sum of its proper divisors (40442724).

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

21015036 is a wasteful number, since it uses less digits than its factorization.

21015036 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1043 (or 1038 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

The square root of 21015036 is about 4584.2159634991. The cubic root of 21015036 is about 275.9582482527.

Adding to 21015036 its reverse (63051012), we get a palindrome (84066048).

The spelling of 21015036 in words is "twenty-one million, fifteen thousand, thirty-six".