21428135 has 4 divisors (see below), whose sum is σ = 25713768. Its totient is φ = 17142504.

The previous prime is 21428131. The next prime is 21428153. The reversal of 21428135 is 53182412.

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 21428135 - 2² = 21428131 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 (21428131) 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, 2142809 + ... + 2142818.

It is an arithmetic number, because the mean of its divisors is an integer number (6428442).

Almost surely, 2^21428135 is an apocalyptic number.

21428135 is a deficient number, since it is larger than the sum of its proper divisors (4285633).

21428135 is an equidigital number, since it uses as much as digits as its factorization.

21428135 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4285632.

The product of its digits is 1920, while the sum is 26.

The square root of 21428135 is about 4629.0533589493. The cubic root of 21428135 is about 277.7547264723.

The spelling of 21428135 in words is "twenty-one million, four hundred twenty-eight thousand, one hundred thirty-five".