20870639 has 2 divisors, whose sum is σ = 20870640. Its totient is φ = 20870638.

The previous prime is 20870623. The next prime is 20870653. The reversal of 20870639 is 93607802.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20870639 - 2⁴ = 20870623 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20870599 and 20870608.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20870659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10435319 + 10435320.

It is an arithmetic number, because the mean of its divisors is an integer number (10435320).

Almost surely, 2^20870639 is an apocalyptic number.

20870639 is a deficient number, since it is larger than the sum of its proper divisors (1).

20870639 is an equidigital number, since it uses as much as digits as its factorization.

20870639 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18144, while the sum is 35.

The square root of 20870639 is about 4568.4394490898. The cubic root of 20870639 is about 275.3247469346.

The spelling of 20870639 in words is "twenty million, eight hundred seventy thousand, six hundred thirty-nine".