20531999 has 2 divisors, whose sum is σ = 20532000. Its totient is φ = 20531998.

The previous prime is 20531983. The next prime is 20532011. The reversal of 20531999 is 99913502.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20531999 - 2⁴ = 20531983 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20531099) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10265999 + 10266000.

It is an arithmetic number, because the mean of its divisors is an integer number (10266000).

Almost surely, 2^20531999 is an apocalyptic number.

20531999 is a deficient number, since it is larger than the sum of its proper divisors (1).

20531999 is an equidigital number, since it uses as much as digits as its factorization.

20531999 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 21870, while the sum is 38.

The square root of 20531999 is about 4531.2248895856. The cubic root of 20531999 is about 273.8275105604.

The spelling of 20531999 in words is "twenty million, five hundred thirty-one thousand, nine hundred ninety-nine".