20939867261 has 4 divisors (see below), whose sum is σ = 20948427072. Its totient is φ = 20931307452.

The previous prime is 20939867257. The next prime is 20939867279. The reversal of 20939867261 is 16276893902.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20939867261 - 2² = 20939867257 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20939863261) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4276235 + ... + 4281128.

It is an arithmetic number, because the mean of its divisors is an integer number (5237106768).

Almost surely, 2^20939867261 is an apocalyptic number.

It is an amenable number.

20939867261 is a deficient number, since it is larger than the sum of its proper divisors (8559811).

20939867261 is an equidigital number, since it uses as much as digits as its factorization.

20939867261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8559810.

The product of its (nonzero) digits is 1959552, while the sum is 53.

The spelling of 20939867261 in words is "twenty billion, nine hundred thirty-nine million, eight hundred sixty-seven thousand, two hundred sixty-one".