99661590 has 216 divisors, whose sum is σ = 323099712. Its totient is φ = 22044960.

The previous prime is 99661589. The next prime is 99661591. The reversal of 99661590 is 9516699.

It is an interprime number because it is at equal distance from previous prime (99661589) and next prime (99661591).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99661591) by changing a digit.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 3214875 + ... + 3214905.

It is an arithmetic number, because the mean of its divisors is an integer number (1495832).

Almost surely, 2^99661590 is an apocalyptic number.

99661590 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 99661590, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (161549856).

99661590 is an abundant number, since it is smaller than the sum of its proper divisors (223438122).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

99661590 is an equidigital number, since it uses as much as digits as its factorization.

99661590 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76 (or 48 counting only the distinct ones).

The product of its (nonzero) digits is 131220, while the sum is 45.

The square root of 99661590 is about 9983.0651605607. The cubic root of 99661590 is about 463.6347049327.

The spelling of 99661590 in words is "ninety-nine million, six hundred sixty-one thousand, five hundred ninety".