21288053 has 4 divisors (see below), whose sum is σ = 21783168. Its totient is φ = 20792940.

The previous prime is 21288049. The next prime is 21288067. The reversal of 21288053 is 35088212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21288053 - 2² = 21288049 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 (21288013) 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, 247493 + ... + 247578.

It is an arithmetic number, because the mean of its divisors is an integer number (5445792).

Almost surely, 2^21288053 is an apocalyptic number.

It is an amenable number.

21288053 is a deficient number, since it is larger than the sum of its proper divisors (495115).

21288053 is an equidigital number, since it uses as much as digits as its factorization.

21288053 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 495114.

The product of its (nonzero) digits is 3840, while the sum is 29.

The square root of 21288053 is about 4613.8978098783. The cubic root of 21288053 is about 277.1481480626.

The spelling of 21288053 in words is "twenty-one million, two hundred eighty-eight thousand, fifty-three".