20858678777 has 4 divisors (see below), whose sum is σ = 20869653156. Its totient is φ = 20847704400.

The previous prime is 20858678767. The next prime is 20858678837. The reversal of 20858678777 is 77787685802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 77787685802 = 2 ⋅38893842901.

It can be written as a sum of positive squares in 2 ways, for example, as 5508459961 + 15350218816 = 74219^2 + 123896^2 .

It is a cyclic number.

It is not a de Polignac number, because 20858678777 - 2³⁰ = 19784936953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20858678747) 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, 5484338 + ... + 5488139.

It is an arithmetic number, because the mean of its divisors is an integer number (5217413289).

Almost surely, 2^20858678777 is an apocalyptic number.

It is an amenable number.

20858678777 is a deficient number, since it is larger than the sum of its proper divisors (10974379).

20858678777 is a wasteful number, since it uses less digits than its factorization.

20858678777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10974378.

The product of its (nonzero) digits is 73758720, while the sum is 65.

The spelling of 20858678777 in words is "twenty billion, eight hundred fifty-eight million, six hundred seventy-eight thousand, seven hundred seventy-seven".