103920021 has 18 divisors (see below), whose sum is σ = 155529270. Its totient is φ = 66785040.

The previous prime is 103919999. The next prime is 103920041. The reversal of 103920021 is 120029301.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 89586225 + 14333796 = 9465^2 + 3786^2 .

It is not a de Polignac number, because 103920021 - 2¹⁴ = 103903637 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 103919976 and 103920003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (103920041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 164376 + ... + 165006.

It is an arithmetic number, because the mean of its divisors is an integer number (8640515).

Almost surely, 2^103920021 is an apocalyptic number.

It is an amenable number.

103920021 is a deficient number, since it is larger than the sum of its proper divisors (51609249).

103920021 is an frugal number, since it uses more digits than its factorization.

103920021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1297 (or 663 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 103920021 is about 10194.1169799056. The cubic root of 103920021 is about 470.1463570154.

Adding to 103920021 its reverse (120029301), we get a palindrome (223949322).

The spelling of 103920021 in words is "one hundred three million, nine hundred twenty thousand, twenty-one".