20917880 has 16 divisors (see below), whose sum is σ = 47065320. Its totient is φ = 8367136.

The previous prime is 20917873. The next prime is 20917889. The reversal of 20917880 is 8871902.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 20917880.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20917889) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 261434 + ... + 261513.

Almost surely, 2^20917880 is an apocalyptic number.

20917880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20917880 is an abundant number, since it is smaller than the sum of its proper divisors (26147440).

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

20917880 is a wasteful number, since it uses less digits than its factorization.

20917880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 522958 (or 522954 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 35.

The square root of 20917880 is about 4573.6068917212. The cubic root of 20917880 is about 275.5323242738.

The spelling of 20917880 in words is "twenty million, nine hundred seventeen thousand, eight hundred eighty".