21154235 has 4 divisors (see below), whose sum is σ = 25385088. Its totient is φ = 16923384.

The previous prime is 21154207. The next prime is 21154283. The reversal of 21154235 is 53245112.

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 21154235 - 2¹² = 21150139 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21154235.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2115419 + ... + 2115428.

It is an arithmetic number, because the mean of its divisors is an integer number (6346272).

Almost surely, 2^21154235 is an apocalyptic number.

21154235 is a deficient number, since it is larger than the sum of its proper divisors (4230853).

21154235 is an equidigital number, since it uses as much as digits as its factorization.

21154235 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4230852.

The product of its digits is 1200, while the sum is 23.

The square root of 21154235 is about 4599.3733268783. The cubic root of 21154235 is about 276.5662035849.

Adding to 21154235 its reverse (53245112), we get a palindrome (74399347).

The spelling of 21154235 in words is "twenty-one million, one hundred fifty-four thousand, two hundred thirty-five".