21221088 has 96 divisors (see below), whose sum is σ = 66479616. Its totient is φ = 5795328.

The previous prime is 21221077. The next prime is 21221099. The reversal of 21221088 is 88012212.

It is an interprime number because it is at equal distance from previous prime (21221077) and next prime (21221099).

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

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, 14770 + ... + 16142.

It is an arithmetic number, because the mean of its divisors is an integer number (692496).

Almost surely, 2^21221088 is an apocalyptic number.

21221088 is a gapful number since it is divisible by the number (28) 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 21221088, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33239808).

21221088 is an abundant number, since it is smaller than the sum of its proper divisors (45258528).

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

21221088 is a wasteful number, since it uses less digits than its factorization.

21221088 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1416 (or 1408 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 21221088 is about 4606.6352145574. The cubic root of 21221088 is about 276.8572380992.

The spelling of 21221088 in words is "twenty-one million, two hundred twenty-one thousand, eighty-eight".