20581764 has 144 divisors (see below), whose sum is σ = 62052480. Its totient is φ = 5268480.

The previous prime is 20581721. The next prime is 20581777. The reversal of 20581764 is 46718502.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 289849 + ... + 289919.

It is an arithmetic number, because the mean of its divisors is an integer number (430920).

Almost surely, 2^20581764 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 20581764, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31026240).

20581764 is an abundant number, since it is smaller than the sum of its proper divisors (41470716).

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

20581764 is a wasteful number, since it uses less digits than its factorization.

20581764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138 (or 129 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 20581764 is about 4536.7129069404. The cubic root of 20581764 is about 274.0485643934.

The spelling of 20581764 in words is "twenty million, five hundred eighty-one thousand, seven hundred sixty-four".