20868507257 has 8 divisors (see below), whose sum is σ = 22524976320. Its totient is φ = 19219352400.

The previous prime is 20868507251. The next prime is 20868507263. The reversal of 20868507257 is 75270586802.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (20868507251) and next prime (20868507263).

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

It is a cyclic number.

It is not a de Polignac number, because 20868507257 - 2⁴ = 20868507241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20868507251) 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, 1822619 + ... + 1834032.

It is an arithmetic number, because the mean of its divisors is an integer number (2815622040).

Almost surely, 2^20868507257 is an apocalyptic number.

It is an amenable number.

20868507257 is a deficient number, since it is larger than the sum of its proper divisors (1656469063).

20868507257 is a wasteful number, since it uses less digits than its factorization.

20868507257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3657103.

The product of its (nonzero) digits is 1881600, while the sum is 50.

The spelling of 20868507257 in words is "twenty billion, eight hundred sixty-eight million, five hundred seven thousand, two hundred fifty-seven".