20999220 has 48 divisors (see below), whose sum is σ = 64145088. Its totient is φ = 5090560.

The previous prime is 20999203. The next prime is 20999243. The reversal of 20999220 is 2299902.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15249 + ... + 16568.

It is an arithmetic number, because the mean of its divisors is an integer number (1336356).

Almost surely, 2^20999220 is an apocalyptic number.

20999220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20999220 is an abundant number, since it is smaller than the sum of its proper divisors (43145868).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20999220 is a wasteful number, since it uses less digits than its factorization.

20999220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31840 (or 31838 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 33.

The square root of 20999220 is about 4582.4905891884. The cubic root of 20999220 is about 275.8890017849.

It can be divided in two parts, 209992 and 20, that added together give a palindrome (210012).

The spelling of 20999220 in words is "twenty million, nine hundred ninety-nine thousand, two hundred twenty".