20647957 has 4 divisors (see below), whose sum is σ = 22525056. Its totient is φ = 18770860.

The previous prime is 20647943. The next prime is 20647967. The reversal of 20647957 is 75974602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20647957 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20647967) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 938533 + ... + 938554.

It is an arithmetic number, because the mean of its divisors is an integer number (5631264).

Almost surely, 2^20647957 is an apocalyptic number.

It is an amenable number.

20647957 is a deficient number, since it is larger than the sum of its proper divisors (1877099).

20647957 is a wasteful number, since it uses less digits than its factorization.

20647957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1877098.

The product of its (nonzero) digits is 105840, while the sum is 40.

The square root of 20647957 is about 4544.0023107388. The cubic root of 20647957 is about 274.3420391495.

The spelling of 20647957 in words is "twenty million, six hundred forty-seven thousand, nine hundred fifty-seven".