20017639 has 2 divisors, whose sum is σ = 20017640. Its totient is φ = 20017638.

The previous prime is 20017637. The next prime is 20017649. The reversal of 20017639 is 93671002.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20017639 - 2¹ = 20017637 is a prime.

It is a super-2 number, since 2×20017639² = 801411742268642, which contains 22 as substring.

Together with 20017637, it forms a pair of twin primes.

It is equal to p_1271665 and since 20017639 and 1271665 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20017631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10008819 + 10008820.

It is an arithmetic number, because the mean of its divisors is an integer number (10008820).

Almost surely, 2^20017639 is an apocalyptic number.

20017639 is a deficient number, since it is larger than the sum of its proper divisors (1).

20017639 is an equidigital number, since it uses as much as digits as its factorization.

20017639 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2268, while the sum is 28.

The square root of 20017639 is about 4474.1076205205. The cubic root of 20017639 is about 271.5215375652.

The spelling of 20017639 in words is "twenty million, seventeen thousand, six hundred thirty-nine".