21021088 has 72 divisors (see below), whose sum is σ = 46754820. Its totient is φ = 9292800.

The previous prime is 21021083. The next prime is 21021101. The reversal of 21021088 is 88012012.

It can be written as a sum of positive squares in 2 ways, for example, as 16744464 + 4276624 = 4092^2 + 2068^2 .

It is a super-2 number, since 2×21021088² = 883772281407488, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is not an unprimeable number, because it can be changed into a prime (21021083) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 236148 + ... + 236236.

Almost surely, 2^21021088 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 21021088, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23377410).

21021088 is an abundant number, since it is smaller than the sum of its proper divisors (25733732).

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

21021088 is a wasteful number, since it uses less digits than its factorization.

21021088 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 182 (or 163 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 22.

The square root of 21021088 is about 4584.8760070475. The cubic root of 21021088 is about 275.9847362559.

The spelling of 21021088 in words is "twenty-one million, twenty-one thousand, eighty-eight".