7864156921 has 4 divisors (see below), whose sum is σ = 7971885172. Its totient is φ = 7756428672.

The previous prime is 7864156919. The next prime is 7864156931. The reversal of 7864156921 is 1296514687.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1430352400 + 6433804521 = 37820^2 + 80211^2 .

It is a cyclic number.

It is not a de Polignac number, because 7864156921 - 2¹ = 7864156919 is a prime.

It is a super-2 number, since 2×7864156921² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7864156931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53864016 + ... + 53864161.

It is an arithmetic number, because the mean of its divisors is an integer number (1992971293).

Almost surely, 2^7864156921 is an apocalyptic number.

It is an amenable number.

7864156921 is a deficient number, since it is larger than the sum of its proper divisors (107728251).

7864156921 is a wasteful number, since it uses less digits than its factorization.

7864156921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107728250.

The product of its digits is 725760, while the sum is 49.

The square root of 7864156921 is about 88680.0818729888. The cubic root of 7864156921 is about 1988.6150579372.

The spelling of 7864156921 in words is "seven billion, eight hundred sixty-four million, one hundred fifty-six thousand, nine hundred twenty-one".