21296661 has 4 divisors (see below), whose sum is σ = 28395552. Its totient is φ = 14197772.

The previous prime is 21296651. The next prime is 21296669. The reversal of 21296661 is 16669212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21296661 - 2⁷ = 21296533 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21296669) 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, 3549441 + ... + 3549446.

It is an arithmetic number, because the mean of its divisors is an integer number (7098888).

Almost surely, 2^21296661 is an apocalyptic number.

It is an amenable number.

21296661 is a deficient number, since it is larger than the sum of its proper divisors (7098891).

21296661 is an equidigital number, since it uses as much as digits as its factorization.

21296661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7098890.

The product of its digits is 7776, while the sum is 33.

The square root of 21296661 is about 4614.8305494352. The cubic root of 21296661 is about 277.1854987427.

The spelling of 21296661 in words is "twenty-one million, two hundred ninety-six thousand, six hundred sixty-one".