11978581 has 2 divisors, whose sum is σ = 11978582. Its totient is φ = 11978580.

The previous prime is 11978579. The next prime is 11978587. The reversal of 11978581 is 18587911.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9548100 + 2430481 = 3090^2 + 1559^2 .

It is a cyclic number.

It is not a de Polignac number, because 11978581 - 2¹ = 11978579 is a prime.

It is a super-2 number, since 2×11978581² = 286972805547122, which contains 22 as substring.

Together with 11978579, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11978587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5989290 + 5989291.

It is an arithmetic number, because the mean of its divisors is an integer number (5989291).

Almost surely, 2^11978581 is an apocalyptic number.

It is an amenable number.

11978581 is a deficient number, since it is larger than the sum of its proper divisors (1).

11978581 is an equidigital number, since it uses as much as digits as its factorization.

11978581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20160, while the sum is 40.

The square root of 11978581 is about 3461.0086680042. The cubic root of 11978581 is about 228.8065527509.

The spelling of 11978581 in words is "eleven million, nine hundred seventy-eight thousand, five hundred eighty-one".