20217904 has 40 divisors (see below), whose sum is σ = 45254048. Its totient is φ = 8570880.

The previous prime is 20217839. The next prime is 20217931. The reversal of 20217904 is 40971202.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9934 + ... + 11794.

Almost surely, 2^20217904 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20217904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22627024).

20217904 is an abundant number, since it is smaller than the sum of its proper divisors (25036144).

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

20217904 is a wasteful number, since it uses less digits than its factorization.

20217904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1973 (or 1967 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 20217904 is about 4496.4323635522. The cubic root of 20217904 is about 272.4240070900.

The spelling of 20217904 in words is "twenty million, two hundred seventeen thousand, nine hundred four".