20618431 has 4 divisors (see below), whose sum is σ = 21007512. Its totient is φ = 20229352.

The previous prime is 20618407. The next prime is 20618453. The reversal of 20618431 is 13481602.

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 20618431 - 2¹¹ = 20616383 is a prime.

It is a super-2 number, since 2×20618431² = 850239393803522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20618396 and 20618405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20618491) 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, 194461 + ... + 194566.

It is an arithmetic number, because the mean of its divisors is an integer number (5251878).

Almost surely, 2^20618431 is an apocalyptic number.

20618431 is a deficient number, since it is larger than the sum of its proper divisors (389081).

20618431 is an equidigital number, since it uses as much as digits as its factorization.

20618431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 389080.

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 20618431 is about 4540.7522504537. The cubic root of 20618431 is about 274.2112096256.

The spelling of 20618431 in words is "twenty million, six hundred eighteen thousand, four hundred thirty-one".