20891080 has 32 divisors (see below), whose sum is σ = 53720640. Its totient is φ = 7162560.

The previous prime is 20891071. The next prime is 20891081. The reversal of 20891080 is 8019802.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is not an unprimeable number, because it can be changed into a prime (20891081) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 37026 + ... + 37585.

It is an arithmetic number, because the mean of its divisors is an integer number (1678770).

Almost surely, 2^20891080 is an apocalyptic number.

20891080 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20891080 is an abundant number, since it is smaller than the sum of its proper divisors (32829560).

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

20891080 is a wasteful number, since it uses less digits than its factorization.

20891080 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74629 (or 74625 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 28.

The square root of 20891080 is about 4570.6760987845. The cubic root of 20891080 is about 275.4146032601.

The spelling of 20891080 in words is "twenty million, eight hundred ninety-one thousand, eighty".