21154355 has 4 divisors (see below), whose sum is σ = 25385232. Its totient is φ = 16923480.

The previous prime is 21154339. The next prime is 21154381. The reversal of 21154355 is 55345112.

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

It is not a de Polignac number, because 21154355 - 2⁴ = 21154339 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2115431 + ... + 2115440.

It is an arithmetic number, because the mean of its divisors is an integer number (6346308).

Almost surely, 2^21154355 is an apocalyptic number.

21154355 is a deficient number, since it is larger than the sum of its proper divisors (4230877).

21154355 is an equidigital number, since it uses as much as digits as its factorization.

21154355 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4230876.

The product of its digits is 3000, while the sum is 26.

The square root of 21154355 is about 4599.3863721153. The cubic root of 21154355 is about 276.5667265359.

Adding to 21154355 its reverse (55345112), we get a palindrome (76499467).

The spelling of 21154355 in words is "twenty-one million, one hundred fifty-four thousand, three hundred fifty-five".