3781415521 has 4 divisors (see below), whose sum is σ = 4072293652. Its totient is φ = 3490537392.

The previous prime is 3781415507. The next prime is 3781415543. The reversal of 3781415521 is 1255141873.

3781415521 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is the 25105-th star number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 528310225 + 3253105296 = 22985^2 + 57036^2 .

It is a cyclic number.

It is not a de Polignac number, because 3781415521 - 2¹⁵ = 3781382753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3781413521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 145439046 + ... + 145439071.

It is an arithmetic number, because the mean of its divisors is an integer number (1018073413).

Almost surely, 2^3781415521 is an apocalyptic number.

It is an amenable number.

3781415521 is a deficient number, since it is larger than the sum of its proper divisors (290878131).

3781415521 is a wasteful number, since it uses less digits than its factorization.

3781415521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 290878130.

The product of its digits is 33600, while the sum is 37.

The square root of 3781415521 is about 61493.2152436348. The cubic root of 3781415521 is about 1557.9426529669.

It can be divided in two parts, 37814 and 15521, that added together give a palindrome (53335).

The spelling of 3781415521 in words is "three billion, seven hundred eighty-one million, four hundred fifteen thousand, five hundred twenty-one".