7999991531 has 4 divisors (see below), whose sum is σ = 9142847472. Its totient is φ = 6857135592.

The previous prime is 7999991521. The next prime is 7999991539. The reversal of 7999991531 is 1351999997.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 7999991531 - 2¹⁴ = 7999975147 is a prime.

It is a super-2 number, since 2×7999991531² (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 (7999991539) 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, 571427960 + ... + 571427973.

It is an arithmetic number, because the mean of its divisors is an integer number (2285711868).

Almost surely, 2^7999991531 is an apocalyptic number.

7999991531 is a deficient number, since it is larger than the sum of its proper divisors (1142855941).

7999991531 is a wasteful number, since it uses less digits than its factorization.

7999991531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1142855940.

The product of its digits is 6200145, while the sum is 62.

The square root of 7999991531 is about 89442.6717568298. The cubic root of 7999991531 is about 1999.9992942498. Note that the first 3 decimals are identical.

The spelling of 7999991531 in words is "seven billion, nine hundred ninety-nine million, nine hundred ninety-one thousand, five hundred thirty-one".