20678636255991 has 16 divisors (see below), whose sum is σ = 31510472625408. Its totient is φ = 11816299915200.

The previous prime is 20678636255987. The next prime is 20678636256127. The reversal of 20678636255991 is 19955263687602.

It is not a de Polignac number, because 20678636255991 - 2² = 20678636255987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20678636255971) 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, 1488651 + ... + 6601011.

It is an arithmetic number, because the mean of its divisors is an integer number (1969404539088).

Almost surely, 2^{20678636255991} is an apocalyptic number.

20678636255991 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

20678636255991 is a deficient number, since it is larger than the sum of its proper divisors (10831836369417).

20678636255991 is a wasteful number, since it uses less digits than its factorization.

20678636255991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5304982.

The product of its (nonzero) digits is 293932800, while the sum is 69.

The spelling of 20678636255991 in words is "twenty trillion, six hundred seventy-eight billion, six hundred thirty-six million, two hundred fifty-five thousand, nine hundred ninety-one".