20905571231 has 2 divisors, whose sum is σ = 20905571232. Its totient is φ = 20905571230.

The previous prime is 20905571201. The next prime is 20905571261. The reversal of 20905571231 is 13217550902.

It is a balanced prime because it is at equal distance from previous prime (20905571201) and next prime (20905571261).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20905571231 is a prime.

It is a super-2 number, since 2×20905571231² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20905571191 and 20905571200.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20905571201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10452785615 + 10452785616.

It is an arithmetic number, because the mean of its divisors is an integer number (10452785616).

Almost surely, 2^20905571231 is an apocalyptic number.

20905571231 is a deficient number, since it is larger than the sum of its proper divisors (1).

20905571231 is an equidigital number, since it uses as much as digits as its factorization.

20905571231 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18900, while the sum is 35.

The spelling of 20905571231 in words is "twenty billion, nine hundred five million, five hundred seventy-one thousand, two hundred thirty-one".