20871940 has 12 divisors (see below), whose sum is σ = 43831116. Its totient is φ = 8348768.

The previous prime is 20871923. The next prime is 20871973. The reversal of 20871940 is 4917802.

It can be written as a sum of positive squares in 2 ways, for example, as 16128256 + 4743684 = 4016^2 + 2178^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 521779 + ... + 521818.

It is an arithmetic number, because the mean of its divisors is an integer number (3652593).

Almost surely, 2^20871940 is an apocalyptic number.

20871940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20871940 is an abundant number, since it is smaller than the sum of its proper divisors (22959176).

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

20871940 is a wasteful number, since it uses less digits than its factorization.

20871940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1043606 (or 1043604 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 20871940 is about 4568.5818368505. The cubic root of 20871940 is about 275.3304677313.

The spelling of 20871940 in words is "twenty million, eight hundred seventy-one thousand, nine hundred forty".