20691600 has 120 divisors (see below), whose sum is σ = 67992672. Its totient is φ = 5376000.

The previous prime is 20691577. The next prime is 20691607. The reversal of 20691600 is 619602.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (20691607) 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 23 ways as a sum of consecutive naturals, for example, 51400 + ... + 51800.

Almost surely, 2^20691600 is an apocalyptic number.

20691600 is a gapful number since it is divisible by the number (20) 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 20691600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33996336).

20691600 is an abundant number, since it is smaller than the sum of its proper divisors (47301072).

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

20691600 is a wasteful number, since it uses less digits than its factorization.

20691600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 465 (or 454 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 24.

The square root of 20691600 is about 4548.8020400980. The cubic root of 20691600 is about 274.5351927831.

It can be divided in two parts, 206 and 91600, that added together give a triangular number (91806 = T₄₂₈).

The spelling of 20691600 in words is "twenty million, six hundred ninety-one thousand, six hundred".