21140555 has 4 divisors (see below), whose sum is σ = 25368672. Its totient is φ = 16912440.

The previous prime is 21140549. The next prime is 21140569. The reversal of 21140555 is 55504112.

It is a happy number.

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

It is a de Polignac number, because none of the positive numbers 2^k-21140555 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 21140555.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2114051 + ... + 2114060.

It is an arithmetic number, because the mean of its divisors is an integer number (6342168).

Almost surely, 2^21140555 is an apocalyptic number.

21140555 is a deficient number, since it is larger than the sum of its proper divisors (4228117).

21140555 is an equidigital number, since it uses as much as digits as its factorization.

21140555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4228116.

The product of its (nonzero) digits is 1000, while the sum is 23.

The square root of 21140555 is about 4597.8859272496. The cubic root of 21140555 is about 276.5065742087.

Adding to 21140555 its reverse (55504112), we get a palindrome (76644667).

The spelling of 21140555 in words is "twenty-one million, one hundred forty thousand, five hundred fifty-five".