863561521 has 4 divisors (see below), whose sum is σ = 863663472. Its totient is φ = 863459572.

The previous prime is 863561453. The next prime is 863561539. The reversal of 863561521 is 125165368.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-863561521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (863561551) 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 3 ways as a sum of consecutive naturals, for example, 36991 + ... + 55636.

It is an arithmetic number, because the mean of its divisors is an integer number (215915868).

Almost surely, 2^863561521 is an apocalyptic number.

It is an amenable number.

863561521 is a deficient number, since it is larger than the sum of its proper divisors (101951).

863561521 is an equidigital number, since it uses as much as digits as its factorization.

863561521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101950.

The product of its digits is 43200, while the sum is 37.

The square root of 863561521 is about 29386.4172875837. The cubic root of 863561521 is about 952.2794830777.

The spelling of 863561521 in words is "eight hundred sixty-three million, five hundred sixty-one thousand, five hundred twenty-one".