20481551 has 4 divisors (see below), whose sum is σ = 20529504. Its totient is φ = 20433600.

The previous prime is 20481541. The next prime is 20481553. The reversal of 20481551 is 15518402.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20481551 - 2¹⁰ = 20480527 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20481551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20481553) 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 3 ways as a sum of consecutive naturals, for example, 23330 + ... + 24191.

It is an arithmetic number, because the mean of its divisors is an integer number (5132376).

Almost surely, 2^20481551 is an apocalyptic number.

20481551 is a deficient number, since it is larger than the sum of its proper divisors (47953).

20481551 is an equidigital number, since it uses as much as digits as its factorization.

20481551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47952.

The product of its (nonzero) digits is 1600, while the sum is 26.

The square root of 20481551 is about 4525.6547592586. The cubic root of 20481551 is about 273.6030579936.

Adding to 20481551 its reverse (15518402), we get a palindrome (35999953).

The spelling of 20481551 in words is "twenty million, four hundred eighty-one thousand, five hundred fifty-one".