20691984 has 20 divisors (see below), whose sum is σ = 53454416. Its totient is φ = 6897312.

The previous prime is 20691977. The next prime is 20691989. The reversal of 20691984 is 48919602.

It is not an unprimeable number, because it can be changed into a prime (20691989) 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, 215494 + ... + 215589.

Almost surely, 2^20691984 is an apocalyptic number.

20691984 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

20691984 is an abundant number, since it is smaller than the sum of its proper divisors (32762432).

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

20691984 is a wasteful number, since it uses less digits than its factorization.

20691984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 431094 (or 431088 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 39.

The square root of 20691984 is about 4548.8442488175. The cubic root of 20691984 is about 274.5368910707.

The spelling of 20691984 in words is "twenty million, six hundred ninety-one thousand, nine hundred eighty-four".