20639937 has 8 divisors (see below), whose sum is σ = 27570400. Its totient is φ = 13734720.

The previous prime is 20639923. The next prime is 20639939. The reversal of 20639937 is 73993602.

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

It is not a de Polignac number, because 20639937 - 2¹⁶ = 20574401 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20639895 and 20639904.

It is not an unprimeable number, because it can be changed into a prime (20639939) 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, 4312 + ... + 7737.

It is an arithmetic number, because the mean of its divisors is an integer number (3446300).

Almost surely, 2^20639937 is an apocalyptic number.

It is an amenable number.

20639937 is a deficient number, since it is larger than the sum of its proper divisors (6930463).

20639937 is a wasteful number, since it uses less digits than its factorization.

20639937 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12623.

The product of its (nonzero) digits is 61236, while the sum is 39.

The square root of 20639937 is about 4543.1197430840. The cubic root of 20639937 is about 274.3065149233.

The spelling of 20639937 in words is "twenty million, six hundred thirty-nine thousand, nine hundred thirty-seven".