21797117 has 4 divisors (see below), whose sum is σ = 22328796. Its totient is φ = 21265440.

The previous prime is 21797093. The next prime is 21797119. The reversal of 21797117 is 71179712.

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 12880921 + 8916196 = 3589^2 + 2986^2 .

It is a cyclic number.

It is not a de Polignac number, because 21797117 - 2⁶ = 21797053 is a prime.

It is a super-2 number, since 2×21797117² = 950228619023378, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21797119) 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, 265778 + ... + 265859.

It is an arithmetic number, because the mean of its divisors is an integer number (5582199).

Almost surely, 2^21797117 is an apocalyptic number.

It is an amenable number.

21797117 is a deficient number, since it is larger than the sum of its proper divisors (531679).

21797117 is an equidigital number, since it uses as much as digits as its factorization.

21797117 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 531678.

The product of its digits is 6174, while the sum is 35.

The square root of 21797117 is about 4668.7382663842. The cubic root of 21797117 is about 279.3399290173.

The spelling of 21797117 in words is "twenty-one million, seven hundred ninety-seven thousand, one hundred seventeen".