11989561 has 4 divisors (see below), whose sum is σ = 12268432. Its totient is φ = 11710692.

The previous prime is 11989553. The next prime is 11989597. The reversal of 11989561 is 16598911.

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 not a de Polignac number, because 11989561 - 2³ = 11989553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11989511) 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, 139371 + ... + 139456.

It is an arithmetic number, because the mean of its divisors is an integer number (3067108).

Almost surely, 2^11989561 is an apocalyptic number.

It is an amenable number.

11989561 is a deficient number, since it is larger than the sum of its proper divisors (278871).

11989561 is an equidigital number, since it uses as much as digits as its factorization.

11989561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 278870.

The product of its digits is 19440, while the sum is 40.

The square root of 11989561 is about 3462.5945474456. The cubic root of 11989561 is about 228.8764421844.

The spelling of 11989561 in words is "eleven million, nine hundred eighty-nine thousand, five hundred sixty-one".