20901931 has 2 divisors, whose sum is σ = 20901932.
Its totient is φ = 20901930.
The previous prime is 20901911. The next prime is 20901941. The reversal of 20901931 is 13910902.
It is a strong prime.
It is a cyclic number.
It is not a de Polignac number, because 20901931 - 213 = 20893739 is a prime.
It is a super-2 number, since 2×209019312 = 873781439057522, which contains 22 as substring.
It is a junction number, because it is equal to n+sod(n) for n = 20901896 and 20901905.
It is not a weakly prime, because it can be changed into another prime (20901901) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10450965 + 10450966.
It is an arithmetic number, because the mean of its divisors is an integer number (10450966).
Almost surely, 220901931 is an apocalyptic number.
20901931 is the 2892-nd centered pentagonal number.
20901931 is a deficient number, since it is larger than the sum of its proper divisors (1).
20901931 is an equidigital number, since it uses as much as digits as its factorization.
20901931 is an evil number, because the sum of its binary digits is even.
The product of its (nonzero) digits is 486, while the sum is 25.
The square root of 20901931 is about 4571.8629682002.
The cubic root of 20901931 is about 275.4622792154.
The spelling of 20901931 in words is "twenty million, nine hundred one thousand, nine hundred thirty-one".