20956659 has 4 divisors (see below), whose sum is σ = 27942216. Its totient is φ = 13971104.

The previous prime is 20956643. The next prime is 20956669. The reversal of 20956659 is 95665902.

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 20956659 - 2⁴ = 20956643 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20956659.

It is not an unprimeable number, because it can be changed into a prime (20956669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3492774 + ... + 3492779.

It is an arithmetic number, because the mean of its divisors is an integer number (6985554).

Almost surely, 2^20956659 is an apocalyptic number.

20956659 is a deficient number, since it is larger than the sum of its proper divisors (6985557).

20956659 is an equidigital number, since it uses as much as digits as its factorization.

20956659 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6985556.

The product of its (nonzero) digits is 145800, while the sum is 42.

The square root of 20956659 is about 4577.8443617056. The cubic root of 20956659 is about 275.7024860686.

The spelling of 20956659 in words is "twenty million, nine hundred fifty-six thousand, six hundred fifty-nine".