21082661 has 4 divisors (see below), whose sum is σ = 21120672. Its totient is φ = 21044652.

The previous prime is 21082631. The next prime is 21082667. The reversal of 21082661 is 16628012.

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 21082661 - 2⁶ = 21082597 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21082661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21082667) 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, 18161 + ... + 19286.

It is an arithmetic number, because the mean of its divisors is an integer number (5280168).

Almost surely, 2^21082661 is an apocalyptic number.

It is an amenable number.

21082661 is a deficient number, since it is larger than the sum of its proper divisors (38011).

21082661 is an equidigital number, since it uses as much as digits as its factorization.

21082661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38010.

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 21082661 is about 4591.5858916065. The cubic root of 21082661 is about 276.2539364590.

The spelling of 21082661 in words is "twenty-one million, eighty-two thousand, six hundred sixty-one".