21728202 has 16 divisors (see below), whose sum is σ = 43770720. Its totient is φ = 7190352.

The previous prime is 21728197. The next prime is 21728233. The reversal of 21728202 is 20282712.

It is a happy number.

It is a super-2 number, since 2×21728202² = 944229524305608, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12193 + ... + 13860.

It is an arithmetic number, because the mean of its divisors is an integer number (2735670).

Almost surely, 2^21728202 is an apocalyptic number.

21728202 is an abundant number, since it is smaller than the sum of its proper divisors (22042518).

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

21728202 is a wasteful number, since it uses less digits than its factorization.

21728202 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26197.

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 21728202 is about 4661.3519498103. The cubic root of 21728202 is about 279.0452259003.

The spelling of 21728202 in words is "twenty-one million, seven hundred twenty-eight thousand, two hundred two".