20909827979 has 16 divisors (see below), whose sum is σ = 22140086400. Its totient is φ = 19715426304.

The previous prime is 20909827937. The next prime is 20909828003. The reversal of 20909827979 is 97972890902.

It is a cyclic number.

It is not a de Polignac number, because 20909827979 - 2³² = 16614860683 is a prime.

It is a super-2 number, since 2×20909827979² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20909824979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 606107 + ... + 639675.

It is an arithmetic number, because the mean of its divisors is an integer number (1383755400).

Almost surely, 2^20909827979 is an apocalyptic number.

20909827979 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

20909827979 is a deficient number, since it is larger than the sum of its proper divisors (1230258421).

20909827979 is a wasteful number, since it uses less digits than its factorization.

20909827979 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34102.

The product of its (nonzero) digits is 10287648, while the sum is 62.

The spelling of 20909827979 in words is "twenty billion, nine hundred nine million, eight hundred twenty-seven thousand, nine hundred seventy-nine".