21053351 has 4 divisors (see below), whose sum is σ = 22967304. Its totient is φ = 19139400.

The previous prime is 21053323. The next prime is 21053353. The reversal of 21053351 is 15335012.

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 21053351 - 2⁶ = 21053287 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 (21053353) 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, 956960 + ... + 956981.

It is an arithmetic number, because the mean of its divisors is an integer number (5741826).

Almost surely, 2^21053351 is an apocalyptic number.

21053351 is a deficient number, since it is larger than the sum of its proper divisors (1913953).

21053351 is a wasteful number, since it uses less digits than its factorization.

21053351 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1913952.

The product of its (nonzero) digits is 450, while the sum is 20.

The square root of 21053351 is about 4588.3930738331. The cubic root of 21053351 is about 276.1258571487.

Adding to 21053351 its reverse (15335012), we get a palindrome (36388363).

The spelling of 21053351 in words is "twenty-one million, fifty-three thousand, three hundred fifty-one".