181668690 has 128 divisors (see below), whose sum is σ = 582912000. Its totient is φ = 39331008.

The previous prime is 181668661. The next prime is 181668703. The reversal of 181668690 is 96866181.

It is a happy number.

It is a super-2 number, since 2×181668690² = 66007025852632200, which contains 22 as substring.

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

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 33381 + ... + 38439.

It is an arithmetic number, because the mean of its divisors is an integer number (4554000).

Almost surely, 2^181668690 is an apocalyptic number.

181668690 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 181668690, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (291456000).

181668690 is an abundant number, since it is smaller than the sum of its proper divisors (401243310).

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

181668690 is a wasteful number, since it uses less digits than its factorization.

181668690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5101 (or 5095 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The square root of 181668690 is about 13478.4528043837. The cubic root of 181668690 is about 566.3610281825.

The spelling of 181668690 in words is "one hundred eighty-one million, six hundred sixty-eight thousand, six hundred ninety".