20491567 has 2 divisors, whose sum is σ = 20491568. Its totient is φ = 20491566.

The previous prime is 20491561. The next prime is 20491571. The reversal of 20491567 is 76519402.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20491567 - 2⁷ = 20491439 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20491561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10245783 + 10245784.

It is an arithmetic number, because the mean of its divisors is an integer number (10245784).

Almost surely, 2^20491567 is an apocalyptic number.

20491567 is a deficient number, since it is larger than the sum of its proper divisors (1).

20491567 is an equidigital number, since it uses as much as digits as its factorization.

20491567 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15120, while the sum is 34.

The square root of 20491567 is about 4526.7612042165. The cubic root of 20491567 is about 273.6476503464.

The spelling of 20491567 in words is "twenty million, four hundred ninety-one thousand, five hundred sixty-seven".