20581002 has 48 divisors (see below), whose sum is σ = 48347208. Its totient is φ = 6289920.

The previous prime is 20580997. The next prime is 20581003. The reversal of 20581002 is 20018502.

It can be written as a sum of positive squares in 4 ways, for example, as 8946081 + 11634921 = 2991^2 + 3411^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (20581003) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 65598 + ... + 65910.

Almost surely, 2^20581002 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20581002, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24173604).

20581002 is an abundant number, since it is smaller than the sum of its proper divisors (27766206).

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

20581002 is a wasteful number, since it uses less digits than its factorization.

20581002 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 615 (or 612 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 20581002 is about 4536.6289246532. The cubic root of 20581002 is about 274.0451823123.

Adding to 20581002 its reverse (20018502), we get a palindrome (40599504).

Subtracting from 20581002 its reverse (20018502), we obtain a square (562500 = 750²).

The spelling of 20581002 in words is "twenty million, five hundred eighty-one thousand, two".