12991621 has 8 divisors (see below), whose sum is σ = 13789440. Its totient is φ = 12197568.

The previous prime is 12991613. The next prime is 12991661. The reversal of 12991621 is 12619921.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 12991621 - 2³ = 12991613 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12991661) 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 7 ways as a sum of consecutive naturals, for example, 9690 + ... + 10948.

It is an arithmetic number, because the mean of its divisors is an integer number (1723680).

Almost surely, 2^12991621 is an apocalyptic number.

It is an amenable number.

12991621 is a deficient number, since it is larger than the sum of its proper divisors (797819).

12991621 is a wasteful number, since it uses less digits than its factorization.

12991621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1883.

The product of its digits is 1944, while the sum is 31.

The square root of 12991621 is about 3604.3891299359. The cubic root of 12991621 is about 235.0829403933.

The spelling of 12991621 in words is "twelve million, nine hundred ninety-one thousand, six hundred twenty-one".