20777846645 has 4 divisors (see below), whose sum is σ = 24933415980. Its totient is φ = 16622277312.

The previous prime is 20777846623. The next prime is 20777846647. The reversal of 20777846645 is 54664877702.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54664877702 = 2 ⋅27332438851.

It can be written as a sum of positive squares in 2 ways, for example, as 14065485604 + 6712361041 = 118598^2 + 81929^2 .

It is a cyclic number.

It is not a de Polignac number, because 20777846645 - 2²⁰ = 20776798069 is a prime.

It is a super-2 number, since 2×20777846645² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20777846647) 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, 2077784660 + ... + 2077784669.

It is an arithmetic number, because the mean of its divisors is an integer number (6233353995).

Almost surely, 2^20777846645 is an apocalyptic number.

It is an amenable number.

20777846645 is a deficient number, since it is larger than the sum of its proper divisors (4155569335).

20777846645 is an equidigital number, since it uses as much as digits as its factorization.

20777846645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4155569334.

The product of its (nonzero) digits is 15805440, while the sum is 56.

The spelling of 20777846645 in words is "twenty billion, seven hundred seventy-seven million, eight hundred forty-six thousand, six hundred forty-five".