20639895 has 16 divisors (see below), whose sum is σ = 33917280. Its totient is φ = 10710144.

The previous prime is 20639891. The next prime is 20639897. The reversal of 20639895 is 59893602.

It is not a de Polignac number, because 20639895 - 2² = 20639891 is a prime.

It is a super-2 number, since 2×20639895² = 852010531222050, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20639891) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18040 + ... + 19149.

It is an arithmetic number, because the mean of its divisors is an integer number (2119830).

Almost surely, 2^20639895 is an apocalyptic number.

20639895 is a deficient number, since it is larger than the sum of its proper divisors (13277385).

20639895 is a wasteful number, since it uses less digits than its factorization.

20639895 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37234.

The product of its (nonzero) digits is 116640, while the sum is 42.

The square root of 20639895 is about 4543.1151207074. The cubic root of 20639895 is about 274.3063288620.

The spelling of 20639895 in words is "twenty million, six hundred thirty-nine thousand, eight hundred ninety-five".