20991248 has 20 divisors (see below), whose sum is σ = 41187840. Its totient is φ = 10362144.

The previous prime is 20991241. The next prime is 20991263. The reversal of 20991248 is 84219902.

It is not an unprimeable number, because it can be changed into a prime (20991241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7040 + ... + 9567.

It is an arithmetic number, because the mean of its divisors is an integer number (2059392).

Almost surely, 2^20991248 is an apocalyptic number.

It is an amenable number.

20991248 is a deficient number, since it is larger than the sum of its proper divisors (20196592).

20991248 is a wasteful number, since it uses less digits than its factorization.

20991248 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16694 (or 16688 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 20991248 is about 4581.6206739537. The cubic root of 20991248 is about 275.8540851626.

The spelling of 20991248 in words is "twenty million, nine hundred ninety-one thousand, two hundred forty-eight".