9961509531 has 8 divisors (see below), whose sum is σ = 13291287120. Its totient is φ = 6636369152.

The previous prime is 9961509511. The next prime is 9961509587. The reversal of 9961509531 is 1359051699.

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 9961509531 - 2²⁶ = 9894400667 is a prime.

It is a super-2 number, since 2×9961509531² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (9961509511) 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, 1154286 + ... + 1162883.

It is an arithmetic number, because the mean of its divisors is an integer number (1661410890).

Almost surely, 2^9961509531 is an apocalyptic number.

9961509531 is a deficient number, since it is larger than the sum of its proper divisors (3329777589).

9961509531 is a wasteful number, since it uses less digits than its factorization.

9961509531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2318605.

The product of its (nonzero) digits is 328050, while the sum is 48.

The square root of 9961509531 is about 99807.3621082132. The cubic root of 9961509531 is about 2151.6669625627. Note that the first 3 decimals are identical.

The spelling of 9961509531 in words is "nine billion, nine hundred sixty-one million, five hundred nine thousand, five hundred thirty-one".