11638981 has 4 divisors (see below), whose sum is σ = 12014464. Its totient is φ = 11263500.

The previous prime is 11638973. The next prime is 11638993. The reversal of 11638981 is 18983611.

11638981 = T₈₅₁ + T₈₅₂ + ... + T₈₈₁.

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 11638981 - 2³ = 11638973 is a prime.

It is a super-2 number, since 2×11638981² = 270931757436722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 11638981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11638951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 187695 + ... + 187756.

It is an arithmetic number, because the mean of its divisors is an integer number (3003616).

Almost surely, 2^11638981 is an apocalyptic number.

It is an amenable number.

11638981 is a deficient number, since it is larger than the sum of its proper divisors (375483).

11638981 is an equidigital number, since it uses as much as digits as its factorization.

11638981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 375482.

The product of its digits is 10368, while the sum is 37.

The square root of 11638981 is about 3411.5950814831. The cubic root of 11638981 is about 226.6235228823.

The spelling of 11638981 in words is "eleven million, six hundred thirty-eight thousand, nine hundred eighty-one".