21099736 has 32 divisors (see below), whose sum is σ = 45361440. Its totient is φ = 9013248.

The previous prime is 21099719. The next prime is 21099739. The reversal of 21099736 is 63799012.

It is a junction number, because it is equal to n+sod(n) for n = 21099695 and 21099704.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21099739) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31986 + ... + 32638.

It is an arithmetic number, because the mean of its divisors is an integer number (1417545).

Almost surely, 2^21099736 is an apocalyptic number.

It is an amenable number.

21099736 is an abundant number, since it is smaller than the sum of its proper divisors (24261704).

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

21099736 is a wasteful number, since it uses less digits than its factorization.

21099736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1243 (or 1239 counting only the distinct ones).

The product of its (nonzero) digits is 20412, while the sum is 37.

The square root of 21099736 is about 4593.4448946297. Note that the first 3 decimals coincide. The cubic root of 21099736 is about 276.3284963558.

The spelling of 21099736 in words is "twenty-one million, ninety-nine thousand, seven hundred thirty-six".