20581251 has 16 divisors (see below), whose sum is σ = 28740096. Its totient is φ = 13076096.

The previous prime is 20581243. The next prime is 20581259. The reversal of 20581251 is 15218502.

It is an interprime number because it is at equal distance from previous prime (20581243) and next prime (20581259).

It is a cyclic number.

It is not a de Polignac number, because 20581251 - 2³ = 20581243 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20581259) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34411 + ... + 35003.

It is an arithmetic number, because the mean of its divisors is an integer number (1796256).

Almost surely, 2^20581251 is an apocalyptic number.

20581251 is a deficient number, since it is larger than the sum of its proper divisors (8158845).

20581251 is a wasteful number, since it uses less digits than its factorization.

20581251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1122.

The product of its (nonzero) digits is 800, while the sum is 24.

The square root of 20581251 is about 4536.6563678551. The cubic root of 20581251 is about 274.0462874897.

Adding to 20581251 its reverse (15218502), we get a palindrome (35799753).

The spelling of 20581251 in words is "twenty million, five hundred eighty-one thousand, two hundred fifty-one".