20778281643 has 16 divisors (see below), whose sum is σ = 31670092800. Its totient is φ = 11870322816.

The previous prime is 20778281639. The next prime is 20778281737. The reversal of 20778281643 is 34618287702.

It is not a de Polignac number, because 20778281643 - 2² = 20778281639 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20778281592 and 20778281601.

It is not an unprimeable number, because it can be changed into a prime (20778271643) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 37155 + ... + 207212.

It is an arithmetic number, because the mean of its divisors is an integer number (1979380800).

Almost surely, 2^20778281643 is an apocalyptic number.

20778281643 is a deficient number, since it is larger than the sum of its proper divisors (10891811157).

20778281643 is a wasteful number, since it uses less digits than its factorization.

20778281643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 248426.

The product of its (nonzero) digits is 903168, while the sum is 48.

The spelling of 20778281643 in words is "twenty billion, seven hundred seventy-eight million, two hundred eighty-one thousand, six hundred forty-three".