99991597 has 4 divisors (see below), whose sum is σ = 100070460. Its totient is φ = 99912736.

The previous prime is 99991583. The next prime is 99991609. The reversal of 99991597 is 79519999.

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 92044836 + 7946761 = 9594^2 + 2819^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-99991597 is a prime.

It is a super-2 number, since 2×99991597² = 19996638941220818, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99991517) 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, 37498 + ... + 40075.

It is an arithmetic number, because the mean of its divisors is an integer number (25017615).

Almost surely, 2^99991597 is an apocalyptic number.

It is an amenable number.

99991597 is a deficient number, since it is larger than the sum of its proper divisors (78863).

99991597 is a wasteful number, since it uses less digits than its factorization.

99991597 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78862.

The product of its digits is 2066715, while the sum is 58.

The square root of 99991597 is about 9999.5798411733. The cubic root of 99991597 is about 464.1458819068.

The spelling of 99991597 in words is "ninety-nine million, nine hundred ninety-one thousand, five hundred ninety-seven".