20356720778 has 8 divisors (see below), whose sum is σ = 30537236100. Its totient is φ = 10177642080.

The previous prime is 20356720757. The next prime is 20356720799. The reversal of 20356720778 is 87702765302.

It is an interprime number because it is at equal distance from previous prime (20356720757) and next prime (20356720799).

It can be written as a sum of positive squares in 2 ways, for example, as 19445465809 + 911254969 = 139447^2 + 30187^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 323003 + ... + 380846.

Almost surely, 2^20356720778 is an apocalyptic number.

20356720778 is a deficient number, since it is larger than the sum of its proper divisors (10180515322).

20356720778 is a wasteful number, since it uses less digits than its factorization.

20356720778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 718312.

The product of its (nonzero) digits is 987840, while the sum is 47.

The spelling of 20356720778 in words is "twenty billion, three hundred fifty-six million, seven hundred twenty thousand, seven hundred seventy-eight".