20691504 has 80 divisors (see below), whose sum is σ = 59936640. Its totient is φ = 6834240.

The previous prime is 20691497. The next prime is 20691509. The reversal of 20691504 is 40519602.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20691509) 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 15 ways as a sum of consecutive naturals, for example, 91039 + ... + 91265.

It is an arithmetic number, because the mean of its divisors is an integer number (749208).

Almost surely, 2^20691504 is an apocalyptic number.

20691504 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20691504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29968320).

20691504 is an abundant number, since it is smaller than the sum of its proper divisors (39245136).

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

20691504 is a wasteful number, since it uses less digits than its factorization.

20691504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 455 (or 443 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 20691504 is about 4548.7914878570. The cubic root of 20691504 is about 274.5347682080.

The spelling of 20691504 in words is "twenty million, six hundred ninety-one thousand, five hundred four".