20991201 has 32 divisors (see below), whose sum is σ = 35229696. Its totient is φ = 10890000.

The previous prime is 20991149. The next prime is 20991211. The reversal of 20991201 is 10219902.

It is not a de Polignac number, because 20991201 - 2¹¹ = 20989153 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20991211) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 27576 + ... + 28326.

It is an arithmetic number, because the mean of its divisors is an integer number (1100928).

Almost surely, 2^20991201 is an apocalyptic number.

20991201 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20991201 is a deficient number, since it is larger than the sum of its proper divisors (14238495).

20991201 is an equidigital number, since it uses as much as digits as its factorization.

20991201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 794 (or 772 counting only the distinct ones).

The product of its (nonzero) digits is 324, while the sum is 24.

The square root of 20991201 is about 4581.6155447615. The cubic root of 20991201 is about 275.8538792808.

The spelling of 20991201 in words is "twenty million, nine hundred ninety-one thousand, two hundred one".