99991553 has 4 divisors (see below), whose sum is σ = 100876548. Its totient is φ = 99106560.

The previous prime is 99991519. The next prime is 99991559. The reversal of 99991553 is 35519999.

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 9684544 + 90307009 = 3112^2 + 9503^2 .

It is a cyclic number.

It is not a de Polignac number, because 99991553 - 2¹² = 99987457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99991559) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 442328 + ... + 442553.

It is an arithmetic number, because the mean of its divisors is an integer number (25219137).

It is a Proth number, since it is equal to 6103 ⋅ 2¹⁴ + 1 and 6103 < 2¹⁴.

Almost surely, 2^99991553 is an apocalyptic number.

It is an amenable number.

99991553 is a deficient number, since it is larger than the sum of its proper divisors (884995).

99991553 is a wasteful number, since it uses less digits than its factorization.

99991553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 884994.

The product of its digits is 492075, while the sum is 50.

The square root of 99991553 is about 9999.5776410806. The cubic root of 99991553 is about 464.1458138263.

The spelling of 99991553 in words is "ninety-nine million, nine hundred ninety-one thousand, five hundred fifty-three".