20639805 has 8 divisors (see below), whose sum is σ = 33023712. Its totient is φ = 11007888.

The previous prime is 20639803. The next prime is 20639807. The reversal of 20639805 is 50893602.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (20639803) and next prime (20639807).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20639805 - 2¹ = 20639803 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20639803) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 687979 + ... + 688008.

It is an arithmetic number, because the mean of its divisors is an integer number (4127964).

Almost surely, 2^20639805 is an apocalyptic number.

It is an amenable number.

20639805 is a deficient number, since it is larger than the sum of its proper divisors (12383907).

20639805 is a wasteful number, since it uses less digits than its factorization.

20639805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1375995.

The product of its (nonzero) digits is 12960, while the sum is 33.

The square root of 20639805 is about 4543.1052155987. The cubic root of 20639805 is about 274.3059301584.

The spelling of 20639805 in words is "twenty million, six hundred thirty-nine thousand, eight hundred five".