21199388 has 24 divisors (see below), whose sum is σ = 42534912. Its totient is φ = 9056304.

The previous prime is 21199369. The next prime is 21199411. The reversal of 21199388 is 88399112.

It is a congruent number.

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, 9245 + ... + 11307.

It is an arithmetic number, because the mean of its divisors is an integer number (1772288).

Almost surely, 2^21199388 is an apocalyptic number.

21199388 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21199388 is an abundant number, since it is smaller than the sum of its proper divisors (21335524).

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

21199388 is a wasteful number, since it uses less digits than its factorization.

21199388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2441 (or 2439 counting only the distinct ones).

The product of its digits is 31104, while the sum is 41.

The square root of 21199388 is about 4604.2793138558. The cubic root of 21199388 is about 276.7628374881.

It can be divided in two parts, 211 and 99388, that added together give a palindrome (99599).

The spelling of 21199388 in words is "twenty-one million, one hundred ninety-nine thousand, three hundred eighty-eight".