20687839 has 2 divisors, whose sum is σ = 20687840. Its totient is φ = 20687838.

The previous prime is 20687803. The next prime is 20687857. The reversal of 20687839 is 93878602.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20687839 - 2¹⁹ = 20163551 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20687795 and 20687804.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20687039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10343919 + 10343920.

It is an arithmetic number, because the mean of its divisors is an integer number (10343920).

Almost surely, 2^20687839 is an apocalyptic number.

20687839 is a deficient number, since it is larger than the sum of its proper divisors (1).

20687839 is an equidigital number, since it uses as much as digits as its factorization.

20687839 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 145152, while the sum is 43.

The square root of 20687839 is about 4548.3886157627. The cubic root of 20687839 is about 274.5185581838.

The spelling of 20687839 in words is "twenty million, six hundred eighty-seven thousand, eight hundred thirty-nine".