21099885 has 16 divisors (see below), whose sum is σ = 34545984. Its totient is φ = 10991232.

The previous prime is 21099863. The next prime is 21099887. The reversal of 21099885 is 58899012.

It is a happy number.

It is not a de Polignac number, because 21099885 - 2⁶ = 21099821 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21099887) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15712 + ... + 17001.

It is an arithmetic number, because the mean of its divisors is an integer number (2159124).

Almost surely, 2^21099885 is an apocalyptic number.

It is an amenable number.

21099885 is a deficient number, since it is larger than the sum of its proper divisors (13446099).

21099885 is a wasteful number, since it uses less digits than its factorization.

21099885 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32764.

The product of its (nonzero) digits is 51840, while the sum is 42.

The square root of 21099885 is about 4593.4611133654. The cubic root of 21099885 is about 276.3291468039.

The spelling of 21099885 in words is "twenty-one million, ninety-nine thousand, eight hundred eighty-five".