20956979 has 4 divisors (see below), whose sum is σ = 21868176. Its totient is φ = 20045784.

The previous prime is 20956973. The next prime is 20956993. The reversal of 20956979 is 97965902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 97965902 = 2 ⋅48982951.

It is a cyclic number.

It is not a de Polignac number, because 20956979 - 2⁴ = 20956963 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20956973) 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, 455564 + ... + 455609.

It is an arithmetic number, because the mean of its divisors is an integer number (5467044).

Almost surely, 2^20956979 is an apocalyptic number.

20956979 is a deficient number, since it is larger than the sum of its proper divisors (911197).

20956979 is an equidigital number, since it uses as much as digits as its factorization.

20956979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 911196.

The product of its (nonzero) digits is 306180, while the sum is 47.

The square root of 20956979 is about 4577.8793125202. The cubic root of 20956979 is about 275.7038893513.

The spelling of 20956979 in words is "twenty million, nine hundred fifty-six thousand, nine hundred seventy-nine".