21211097 has 4 divisors (see below), whose sum is σ = 21248436. Its totient is φ = 21173760.

The previous prime is 21211079. The next prime is 21211109. The reversal of 21211097 is 79011212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 10426441 + 10784656 = 3229^2 + 3284^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211097 - 2⁶ = 21211033 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21211997) 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, 17804 + ... + 18957.

It is an arithmetic number, because the mean of its divisors is an integer number (5312109).

Almost surely, 2^21211097 is an apocalyptic number.

It is an amenable number.

21211097 is a deficient number, since it is larger than the sum of its proper divisors (37339).

21211097 is an equidigital number, since it uses as much as digits as its factorization.

21211097 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37338.

The product of its (nonzero) digits is 252, while the sum is 23.

The square root of 21211097 is about 4605.5506728295. The cubic root of 21211097 is about 276.8137826635.

The spelling of 21211097 in words is "twenty-one million, two hundred eleven thousand, ninety-seven".