99661681 has 8 divisors (see below), whose sum is σ = 113995520. Its totient is φ = 85351968.

The previous prime is 99661663. The next prime is 99661703. The reversal of 99661681 is 18616699.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-99661681 is a prime.

It is a super-2 number, since 2×99661681² = 19864901319491522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99661381) 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, 3925 + ... + 14653.

It is an arithmetic number, because the mean of its divisors is an integer number (14249440).

Almost surely, 2^99661681 is an apocalyptic number.

It is an amenable number.

99661681 is a deficient number, since it is larger than the sum of its proper divisors (14333839).

99661681 is a wasteful number, since it uses less digits than its factorization.

99661681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12063.

The product of its digits is 139968, while the sum is 46.

The square root of 99661681 is about 9983.0697182780. The cubic root of 99661681 is about 463.6348460461.

The spelling of 99661681 in words is "ninety-nine million, six hundred sixty-one thousand, six hundred eighty-one".