20778665594 has 4 divisors (see below), whose sum is σ = 31167998394. Its totient is φ = 10389332796.

The previous prime is 20778665533. The next prime is 20778665603. The reversal of 20778665594 is 49556687702.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 49556687702 = 2 ⋅24778343851.

It can be written as a sum of positive squares in only one way, i.e., 17992198225 + 2786467369 = 134135^2 + 52787^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5194666397 + ... + 5194666400.

Almost surely, 2^20778665594 is an apocalyptic number.

20778665594 is a deficient number, since it is larger than the sum of its proper divisors (10389332800).

20778665594 is a wasteful number, since it uses less digits than its factorization.

20778665594 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10389332799.

The product of its (nonzero) digits is 25401600, while the sum is 59.

The spelling of 20778665594 in words is "twenty billion, seven hundred seventy-eight million, six hundred sixty-five thousand, five hundred ninety-four".