20991125 has 16 divisors (see below), whose sum is σ = 26330304. Its totient is φ = 16707600.

The previous prime is 20991121. The next prime is 20991149. The reversal of 20991125 is 52119902.

It is not a de Polignac number, because 20991125 - 2² = 20991121 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 (20991121) 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, 38102 + ... + 38648.

It is an arithmetic number, because the mean of its divisors is an integer number (1645644).

Almost surely, 2^20991125 is an apocalyptic number.

20991125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20991125 is a deficient number, since it is larger than the sum of its proper divisors (5339179).

20991125 is an equidigital number, since it uses as much as digits as its factorization.

20991125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 869 (or 859 counting only the distinct ones).

The product of its (nonzero) digits is 1620, while the sum is 29.

The square root of 20991125 is about 4581.6072507364. The cubic root of 20991125 is about 275.8535463648.

The spelling of 20991125 in words is "twenty million, nine hundred ninety-one thousand, one hundred twenty-five".