21810697 has 4 divisors (see below), whose sum is σ = 22562820. Its totient is φ = 21058576.

The previous prime is 21810683. The next prime is 21810713. The reversal of 21810697 is 79601812.

It is a happy number.

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 5294601 + 16516096 = 2301^2 + 4064^2 .

It is a cyclic number.

It is not a de Polignac number, because 21810697 - 2¹⁹ = 21286409 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (21810617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 376018 + ... + 376075.

It is an arithmetic number, because the mean of its divisors is an integer number (5640705).

Almost surely, 2^21810697 is an apocalyptic number.

It is an amenable number.

21810697 is a deficient number, since it is larger than the sum of its proper divisors (752123).

21810697 is an equidigital number, since it uses as much as digits as its factorization.

21810697 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 752122.

The product of its (nonzero) digits is 6048, while the sum is 34.

The square root of 21810697 is about 4670.1923943238. The cubic root of 21810697 is about 279.3979282582.

The spelling of 21810697 in words is "twenty-one million, eight hundred ten thousand, six hundred ninety-seven".