20613251 has 4 divisors (see below), whose sum is σ = 20645472. Its totient is φ = 20581032.

The previous prime is 20613239. The next prime is 20613253. The reversal of 20613251 is 15231602.

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 20613251 - 2²² = 16418947 is a prime.

It is a super-2 number, since 2×20613251² = 849812233578002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20613253) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15131 + ... + 16436.

It is an arithmetic number, because the mean of its divisors is an integer number (5161368).

Almost surely, 2^20613251 is an apocalyptic number.

20613251 is a deficient number, since it is larger than the sum of its proper divisors (32221).

20613251 is an equidigital number, since it uses as much as digits as its factorization.

20613251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32220.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 20613251 is about 4540.1818245528. The cubic root of 20613251 is about 274.1882442016.

Adding to 20613251 its reverse (15231602), we get a palindrome (35844853).

The spelling of 20613251 in words is "twenty million, six hundred thirteen thousand, two hundred fifty-one".