3500135721 has 6 divisors (see below), whose sum is σ = 5055751610. Its totient is φ = 2333423808.

The previous prime is 3500135707. The next prime is 3500135759. The reversal of 3500135721 is 1275310053.

3500135721 is a `hidden beast` number, since 3 + 500 + 135 + 7 + 21 = 666.

It can be written as a sum of positive squares in only one way, i.e., 2476455696 + 1023680025 = 49764^2 + 31995^2 .

It is not a de Polignac number, because 3500135721 - 2⁵ = 3500135689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3500135021) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 194451976 + ... + 194451993.

Almost surely, 2^3500135721 is an apocalyptic number.

It is an amenable number.

3500135721 is a deficient number, since it is larger than the sum of its proper divisors (1555615889).

3500135721 is a wasteful number, since it uses less digits than its factorization.

3500135721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 388903975 (or 388903972 counting only the distinct ones).

The product of its (nonzero) digits is 3150, while the sum is 27.

The square root of 3500135721 is about 59161.9448716825. The cubic root of 3500135721 is about 1518.3141108695.

Adding to 3500135721 its reverse (1275310053), we get a palindrome (4775445774).

The spelling of 3500135721 in words is "three billion, five hundred million, one hundred thirty-five thousand, seven hundred twenty-one".