7857936421 has 4 divisors (see below), whose sum is σ = 7860402144. Its totient is φ = 7855470700.

The previous prime is 7857936413. The next prime is 7857936473. The reversal of 7857936421 is 1246397587.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1246397587 = 19 ⋅65599873.

It is a cyclic number.

It is not a de Polignac number, because 7857936421 - 2³ = 7857936413 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7857936481) 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, 1228075 + ... + 1234456.

It is an arithmetic number, because the mean of its divisors is an integer number (1965100536).

Almost surely, 2^7857936421 is an apocalyptic number.

It is an amenable number.

7857936421 is a deficient number, since it is larger than the sum of its proper divisors (2465723).

7857936421 is a wasteful number, since it uses less digits than its factorization.

7857936421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2465722.

The product of its digits is 2540160, while the sum is 52.

The square root of 7857936421 is about 88645.0022336285. The cubic root of 7857936421 is about 1988.0905921826.

The spelling of 7857936421 in words is "seven billion, eight hundred fifty-seven million, nine hundred thirty-six thousand, four hundred twenty-one".