664121515 has 16 divisors (see below), whose sum is σ = 825072768. Its totient is φ = 512856576.

The previous prime is 664121503. The next prime is 664121533. The reversal of 664121515 is 515121466.

It is a cyclic number.

It is not a de Polignac number, because 664121515 - 2⁷ = 664121387 is a prime.

It is a super-3 number, since 3×664121515³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2202 + ... + 36511.

It is an arithmetic number, because the mean of its divisors is an integer number (51567048).

Almost surely, 2^664121515 is an apocalyptic number.

664121515 is a deficient number, since it is larger than the sum of its proper divisors (160951253).

664121515 is a wasteful number, since it uses less digits than its factorization.

664121515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38838.

The product of its digits is 7200, while the sum is 31.

The square root of 664121515 is about 25770.5551938642. Note that the first 3 decimals coincide. The cubic root of 664121515 is about 872.4673496210.

The spelling of 664121515 in words is "six hundred sixty-four million, one hundred twenty-one thousand, five hundred fifteen".