21001136 has 40 divisors (see below), whose sum is σ = 45247104. Its totient is φ = 9377280.

The previous prime is 21001121. The next prime is 21001153. The reversal of 21001136 is 63110012.

It is a self number, because there is not a number n which added to its sum of digits gives 21001136.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4820 + ... + 8076.

Almost surely, 2^21001136 is an apocalyptic number.

21001136 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 21001136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22623552).

21001136 is an abundant number, since it is smaller than the sum of its proper divisors (24245968).

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

21001136 is a wasteful number, since it uses less digits than its factorization.

21001136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3309 (or 3303 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 14.

The square root of 21001136 is about 4582.6996410413. The cubic root of 21001136 is about 275.8973923704.

Adding to 21001136 its reverse (63110012), we get a palindrome (84111148).

The spelling of 21001136 in words is "twenty-one million, one thousand, one hundred thirty-six".