21050205 has 32 divisors (see below), whose sum is σ = 37100160. Its totient is φ = 10106880.

The previous prime is 21050203. The next prime is 21050231. The reversal of 21050205 is 50205012.

It is not a de Polignac number, because 21050205 - 2¹ = 21050203 is a prime.

It is a super-2 number, since 2×21050205² = 886222261084050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21050203) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 18081 + ... + 19209.

It is an arithmetic number, because the mean of its divisors is an integer number (1159380).

Almost surely, 2^21050205 is an apocalyptic number.

It is an amenable number.

21050205 is a deficient number, since it is larger than the sum of its proper divisors (16049955).

21050205 is a wasteful number, since it uses less digits than its factorization.

21050205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1261.

The product of its (nonzero) digits is 100, while the sum is 15.

The square root of 21050205 is about 4588.0502394808. The cubic root of 21050205 is about 276.1121026444.

Adding to 21050205 its reverse (50205012), we get a palindrome (71255217).

The spelling of 21050205 in words is "twenty-one million, fifty thousand, two hundred five".