20856879949 has 12 divisors (see below), whose sum is σ = 22077071100. Its totient is φ = 19691745600.

The previous prime is 20856879907. The next prime is 20856879971. The reversal of 20856879949 is 94997865802.

It can be written as a sum of positive squares in 2 ways, for example, as 610435849 + 20246444100 = 24707^2 + 142290^2 .

It is not a de Polignac number, because 20856879949 - 2⁷ = 20856879821 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20856879049) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 225274 + ... + 304075.

It is an arithmetic number, because the mean of its divisors is an integer number (1839755925).

Almost surely, 2^20856879949 is an apocalyptic number.

It is an amenable number.

20856879949 is a deficient number, since it is larger than the sum of its proper divisors (1220191151).

20856879949 is an equidigital number, since it uses as much as digits as its factorization.

20856879949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 529452 (or 529421 counting only the distinct ones).

The product of its (nonzero) digits is 78382080, while the sum is 67.

The spelling of 20856879949 in words is "twenty billion, eight hundred fifty-six million, eight hundred seventy-nine thousand, nine hundred forty-nine".