123721806 has 64 divisors (see below), whose sum is σ = 289658880. Its totient is φ = 34888320.

The previous prime is 123721781. The next prime is 123721817. The reversal of 123721806 is 608127321.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 44596 + ... + 47288.

It is an arithmetic number, because the mean of its divisors is an integer number (4525920).

Almost surely, 2^123721806 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 123721806, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (144829440).

123721806 is an abundant number, since it is smaller than the sum of its proper divisors (165937074).

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

123721806 is a wasteful number, since it uses less digits than its factorization.

123721806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2761.

The product of its (nonzero) digits is 4032, while the sum is 30.

The square root of 123721806 is about 11123.0304323957. The cubic root of 123721806 is about 498.2898991114.

The spelling of 123721806 in words is "one hundred twenty-three million, seven hundred twenty-one thousand, eight hundred six".