21055311 has 12 divisors (see below), whose sum is σ = 30591288. Its totient is φ = 13954704.

The previous prime is 21055301. The next prime is 21055319. The reversal of 21055311 is 11355012.

It is not a de Polignac number, because 21055311 - 2¹⁰ = 21054287 is a prime.

It is a super-2 number, since 2×21055311² = 886652242613442, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055319) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5205 + ... + 8318.

It is an arithmetic number, because the mean of its divisors is an integer number (2549274).

Almost surely, 2^21055311 is an apocalyptic number.

21055311 is a deficient number, since it is larger than the sum of its proper divisors (9535977).

21055311 is a wasteful number, since it uses less digits than its factorization.

21055311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13702 (or 13699 counting only the distinct ones).

The product of its (nonzero) digits is 150, while the sum is 18.

The square root of 21055311 is about 4588.6066512614. The cubic root of 21055311 is about 276.1344256957.

The spelling of 21055311 in words is "twenty-one million, fifty-five thousand, three hundred eleven".