20509967 has 2 divisors, whose sum is σ = 20509968. Its totient is φ = 20509966.

The previous prime is 20509933. The next prime is 20509981. The reversal of 20509967 is 76990502.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20509967 - 2⁶ = 20509903 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20509967.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20500967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10254983 + 10254984.

It is an arithmetic number, because the mean of its divisors is an integer number (10254984).

Almost surely, 2^20509967 is an apocalyptic number.

20509967 is a deficient number, since it is larger than the sum of its proper divisors (1).

20509967 is an equidigital number, since it uses as much as digits as its factorization.

20509967 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34020, while the sum is 38.

The square root of 20509967 is about 4528.7931063364. The cubic root of 20509967 is about 273.7295313539.

The spelling of 20509967 in words is "twenty million, five hundred nine thousand, nine hundred sixty-seven".