21791211 has 16 divisors (see below), whose sum is σ = 31399200. Its totient is φ = 13363200.

The previous prime is 21791197. The next prime is 21791219. The reversal of 21791211 is 11219712.

It is not a de Polignac number, because 21791211 - 2⁵ = 21791179 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21791219) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12811 + ... + 14411.

It is an arithmetic number, because the mean of its divisors is an integer number (1962450).

Almost surely, 2^21791211 is an apocalyptic number.

21791211 is a deficient number, since it is larger than the sum of its proper divisors (9607989).

21791211 is a wasteful number, since it uses less digits than its factorization.

21791211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1966.

The product of its digits is 252, while the sum is 24.

The square root of 21791211 is about 4668.1057185972. The cubic root of 21791211 is about 279.3146973832.

The spelling of 21791211 in words is "twenty-one million, seven hundred ninety-one thousand, two hundred eleven".