11649981 has 16 divisors (see below), whose sum is σ = 18797184. Its totient is φ = 6265344.

The previous prime is 11649977. The next prime is 11650003. The reversal of 11649981 is 18994611.

It is not a de Polignac number, because 11649981 - 2² = 11649977 is a prime.

It is a super-2 number, since 2×11649981² = 271444114600722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11649901) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15960 + ... + 16673.

It is an arithmetic number, because the mean of its divisors is an integer number (1174824).

Almost surely, 2^11649981 is an apocalyptic number.

It is an amenable number.

11649981 is a deficient number, since it is larger than the sum of its proper divisors (7147203).

11649981 is a wasteful number, since it uses less digits than its factorization.

11649981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32660.

The product of its digits is 15552, while the sum is 39.

The square root of 11649981 is about 3413.2068498701. The cubic root of 11649981 is about 226.6948943604.

The spelling of 11649981 in words is "eleven million, six hundred forty-nine thousand, nine hundred eighty-one".