20661279 has 4 divisors (see below), whose sum is σ = 27548376. Its totient is φ = 13774184.

The previous prime is 20661257. The next prime is 20661287. The reversal of 20661279 is 97216602.

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

It is a cyclic number.

It is not a de Polignac number, because 20661279 - 2⁸ = 20661023 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20661299) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3443544 + ... + 3443549.

It is an arithmetic number, because the mean of its divisors is an integer number (6887094).

Almost surely, 2^20661279 is an apocalyptic number.

20661279 is a deficient number, since it is larger than the sum of its proper divisors (6887097).

20661279 is an equidigital number, since it uses as much as digits as its factorization.

20661279 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6887096.

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 20661279 is about 4545.4679627075. The cubic root of 20661279 is about 274.4010280188.

The spelling of 20661279 in words is "twenty million, six hundred sixty-one thousand, two hundred seventy-nine".