21020255 has 8 divisors (see below), whose sum is σ = 25906272. Its totient is φ = 16361568.

The previous prime is 21020239. The next prime is 21020267. The reversal of 21020255 is 55202012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21020255 - 2⁴ = 21020239 is a prime.

It is a super-2 number, since 2×21020255² = 883702240530050, which contains 22 as substring.

It is a Duffinian number.

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, 56627 + ... + 56996.

It is an arithmetic number, because the mean of its divisors is an integer number (3238284).

Almost surely, 2^21020255 is an apocalyptic number.

21020255 is a deficient number, since it is larger than the sum of its proper divisors (4886017).

21020255 is a wasteful number, since it uses less digits than its factorization.

21020255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113665.

The product of its (nonzero) digits is 200, while the sum is 17.

The square root of 21020255 is about 4584.7851639962. The cubic root of 21020255 is about 275.9810907370.

Adding to 21020255 its reverse (55202012), we get a palindrome (76222267).

The spelling of 21020255 in words is "twenty-one million, twenty thousand, two hundred fifty-five".