521661513 has 8 divisors (see below), whose sum is σ = 697156768. Its totient is φ = 346970304.

The previous prime is 521661499. The next prime is 521661527. The reversal of 521661513 is 315166125.

It is an interprime number because it is at equal distance from previous prime (521661499) and next prime (521661527).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 521661513 - 2²⁴ = 504884297 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (521661593) 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 7 ways as a sum of consecutive naturals, for example, 199495 + ... + 202092.

It is an arithmetic number, because the mean of its divisors is an integer number (87144596).

Almost surely, 2^521661513 is an apocalyptic number.

It is an amenable number.

521661513 is a deficient number, since it is larger than the sum of its proper divisors (175495255).

521661513 is a wasteful number, since it uses less digits than its factorization.

521661513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 402023.

The product of its digits is 5400, while the sum is 30.

The square root of 521661513 is about 22839.9105295971. The cubic root of 521661513 is about 805.0007139636. Note that the first 3 decimals are identical.

The spelling of 521661513 in words is "five hundred twenty-one million, six hundred sixty-one thousand, five hundred thirteen".