21053111 has 4 divisors (see below), whose sum is σ = 21622152. Its totient is φ = 20484072.

The previous prime is 21053107. The next prime is 21053117. The reversal of 21053111 is 11135012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21053111 - 2² = 21053107 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21053117) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 284465 + ... + 284538.

It is an arithmetic number, because the mean of its divisors is an integer number (5405538).

Almost surely, 2^21053111 is an apocalyptic number.

21053111 is a deficient number, since it is larger than the sum of its proper divisors (569041).

21053111 is an equidigital number, since it uses as much as digits as its factorization.

21053111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 569040.

The product of its (nonzero) digits is 30, while the sum is 14.

The square root of 21053111 is about 4588.3669208118. The cubic root of 21053111 is about 276.1248079023.

Adding to 21053111 its reverse (11135012), we get a palindrome (32188123).

The spelling of 21053111 in words is "twenty-one million, fifty-three thousand, one hundred eleven".