20497639 has 2 divisors, whose sum is σ = 20497640. Its totient is φ = 20497638.

The previous prime is 20497621. The next prime is 20497649. The reversal of 20497639 is 93679402.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20497639 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20497619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10248819 + 10248820.

It is an arithmetic number, because the mean of its divisors is an integer number (10248820).

Almost surely, 2^20497639 is an apocalyptic number.

20497639 is a deficient number, since it is larger than the sum of its proper divisors (1).

20497639 is an equidigital number, since it uses as much as digits as its factorization.

20497639 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 81648, while the sum is 40.

The square root of 20497639 is about 4527.4318327281. The cubic root of 20497639 is about 273.6746764956.

The spelling of 20497639 in words is "twenty million, four hundred ninety-seven thousand, six hundred thirty-nine".