97531561 has 4 divisors (see below), whose sum is σ = 97552512.
Its totient is φ = 97510612.
The previous prime is 97531537. The next prime is 97531571. The reversal of 97531561 is 16513579.
97531561 is a nontrivial binomial coefficient, being equal to C(13967, 2).
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: 16513579 = 17 ⋅971387.
It is not a de Polignac number, because 97531561 - 25 = 97531529 is a prime.
It is a super-3 number, since 3×975315613 (a number of 25 digits) contains 333 as substring.
It is a Duffinian number.
It is a self number, because there is not a number n which added to its sum of digits gives 97531561.
It is not an unprimeable number, because it can be changed into a prime (97531531) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (13) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1 + ... + 13966.
It is an arithmetic number, because the mean of its divisors is an integer number (24388128).
Almost surely, 297531561 is an apocalyptic number.
97531561 is the 13966-th triangular number.
97531561 is the 4656-th centered nonagonal number.
It is an amenable number.
97531561 is a deficient number, since it is larger than the sum of its proper divisors (20951).
97531561 is a wasteful number, since it uses less digits than its factorization.
97531561 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 20950.
The product of its digits is 28350, while the sum is 37.
The square root of 97531561 is about 9875.8068531133.
The cubic root of 97531561 is about 460.3078610218.
The spelling of 97531561 in words is "ninety-seven million, five hundred thirty-one thousand, five hundred sixty-one".