21082511 has 4 divisors (see below), whose sum is σ = 21762624. Its totient is φ = 20402400.

The previous prime is 21082483. The next prime is 21082517. The reversal of 21082511 is 11528012.

It is a happy number.

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 21082511 - 2⁶ = 21082447 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 (21082517) 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, 340010 + ... + 340071.

It is an arithmetic number, because the mean of its divisors is an integer number (5440656).

Almost surely, 2^21082511 is an apocalyptic number.

21082511 is a deficient number, since it is larger than the sum of its proper divisors (680113).

21082511 is an equidigital number, since it uses as much as digits as its factorization.

21082511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 680112.

The product of its (nonzero) digits is 160, while the sum is 20.

The square root of 21082511 is about 4591.5695573518. The cubic root of 21082511 is about 276.2532812889.

The spelling of 21082511 in words is "twenty-one million, eighty-two thousand, five hundred eleven".