213617561 has 4 divisors (see below), whose sum is σ = 214042752. Its totient is φ = 213192372.

The previous prime is 213617489. The next prime is 213617581. The reversal of 213617561 is 165716312.

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-213617561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (213617581) 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, 211841 + ... + 212846.

It is an arithmetic number, because the mean of its divisors is an integer number (53510688).

Almost surely, 2^213617561 is an apocalyptic number.

It is an amenable number.

213617561 is a deficient number, since it is larger than the sum of its proper divisors (425191).

213617561 is an equidigital number, since it uses as much as digits as its factorization.

213617561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 425190.

The product of its digits is 7560, while the sum is 32.

The square root of 213617561 is about 14615.6614971749. The cubic root of 213617561 is about 597.7858774489.

The spelling of 213617561 in words is "two hundred thirteen million, six hundred seventeen thousand, five hundred sixty-one".