20313781 has 2 divisors, whose sum is σ = 20313782. Its totient is φ = 20313780.

The previous prime is 20313779. The next prime is 20313809. The reversal of 20313781 is 18731302.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17926756 + 2387025 = 4234^2 + 1545^2 .

It is a cyclic number.

It is not a de Polignac number, because 20313781 - 2¹ = 20313779 is a prime.

It is a super-2 number, since 2×20313781² = 825299397031922, which contains 22 as substring.

Together with 20313779, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20313701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10156890 + 10156891.

It is an arithmetic number, because the mean of its divisors is an integer number (10156891).

Almost surely, 2^20313781 is an apocalyptic number.

It is an amenable number.

20313781 is a deficient number, since it is larger than the sum of its proper divisors (1).

20313781 is an equidigital number, since it uses as much as digits as its factorization.

20313781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 20313781 is about 4507.0812062797. The cubic root of 20313781 is about 272.8539563341.

The spelling of 20313781 in words is "twenty million, three hundred thirteen thousand, seven hundred eighty-one".