20265561091 has 2 divisors, whose sum is σ = 20265561092. Its totient is φ = 20265561090.

The previous prime is 20265561089. The next prime is 20265561223. The reversal of 20265561091 is 19016556202.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20265561091 - 2¹ = 20265561089 is a prime.

It is a super-2 number, since 2×20265561091² (a number of 21 digits) contains 22 as substring.

Together with 20265561089, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 20265561091.

It is not a weakly prime, because it can be changed into another prime (20265562091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10132780545 + 10132780546.

It is an arithmetic number, because the mean of its divisors is an integer number (10132780546).

Almost surely, 2^20265561091 is an apocalyptic number.

20265561091 is a deficient number, since it is larger than the sum of its proper divisors (1).

20265561091 is an equidigital number, since it uses as much as digits as its factorization.

20265561091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32400, while the sum is 37.

The spelling of 20265561091 in words is "twenty billion, two hundred sixty-five million, five hundred sixty-one thousand, ninety-one".