21001512 has 64 divisors (see below), whose sum is σ = 61488000. Its totient is φ = 5852160.

The previous prime is 21001493. The next prime is 21001523. The reversal of 21001512 is 21510012.

It is a super-2 number, since 2×21001512² = 882127012572288, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5364 + ... + 8412.

It is an arithmetic number, because the mean of its divisors is an integer number (960750).

Almost surely, 2^21001512 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 21001512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30744000).

21001512 is an abundant number, since it is smaller than the sum of its proper divisors (40486488).

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

21001512 is a wasteful number, since it uses less digits than its factorization.

21001512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3106 (or 3102 counting only the distinct ones).

The product of its (nonzero) digits is 20, while the sum is 12.

The square root of 21001512 is about 4582.7406647115. The cubic root of 21001512 is about 275.8990388972.

Adding to 21001512 its reverse (21510012), we get a palindrome (42511524).

The spelling of 21001512 in words is "twenty-one million, one thousand, five hundred twelve".