21088436 has 12 divisors (see below), whose sum is σ = 36946980. Its totient is φ = 10532160.

The previous prime is 21088421. The next prime is 21088439. The reversal of 21088436 is 63488012.

It can be written as a sum of positive squares in 2 ways, for example, as 8880400 + 12208036 = 2980^2 + 3494^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21088439) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1760 + ... + 6728.

It is an arithmetic number, because the mean of its divisors is an integer number (3078915).

Almost surely, 2^21088436 is an apocalyptic number.

It is an amenable number.

21088436 is a deficient number, since it is larger than the sum of its proper divisors (15858544).

21088436 is a wasteful number, since it uses less digits than its factorization.

21088436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6034 (or 6032 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 32.

The square root of 21088436 is about 4592.2147162344. The cubic root of 21088436 is about 276.2791581461.

The spelling of 21088436 in words is "twenty-one million, eighty-eight thousand, four hundred thirty-six".