20506831 has 2 divisors, whose sum is σ = 20506832. Its totient is φ = 20506830.

The previous prime is 20506819. The next prime is 20506861. The reversal of 20506831 is 13860502.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20506831 - 2⁹ = 20506319 is a prime.

It is a super-2 number, since 2×20506831² = 841060235325122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20506796 and 20506805.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20506861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10253415 + 10253416.

It is an arithmetic number, because the mean of its divisors is an integer number (10253416).

Almost surely, 2^20506831 is an apocalyptic number.

20506831 is the 2615-th hex number.

20506831 is a deficient number, since it is larger than the sum of its proper divisors (1).

20506831 is an equidigital number, since it uses as much as digits as its factorization.

20506831 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 20506831 is about 4528.4468639921. The cubic root of 20506831 is about 273.7155794452.

The spelling of 20506831 in words is "twenty million, five hundred six thousand, eight hundred thirty-one".