20645724 has 48 divisors (see below), whose sum is σ = 52859520. Its totient is φ = 6219840.

The previous prime is 20645711. The next prime is 20645749. The reversal of 20645724 is 42754602.

It is a junction number, because it is equal to n+sod(n) for n = 20645691 and 20645700.

It is a congruent number.

It is an unprimeable number.

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, 29887 + ... + 30569.

It is an arithmetic number, because the mean of its divisors is an integer number (1101240).

Almost surely, 2^20645724 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 20645724, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26429760).

20645724 is an abundant number, since it is smaller than the sum of its proper divisors (32213796).

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

20645724 is a wasteful number, since it uses less digits than its factorization.

20645724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 930 (or 928 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 30.

The square root of 20645724 is about 4543.7565955936. The cubic root of 20645724 is about 274.3321491015.

The spelling of 20645724 in words is "twenty million, six hundred forty-five thousand, seven hundred twenty-four".