20390351 has 4 divisors (see below), whose sum is σ = 21276912. Its totient is φ = 19503792.

The previous prime is 20390333. The next prime is 20390353. The reversal of 20390351 is 15309302.

It is a happy number.

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 20390351 - 2¹⁴ = 20373967 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23), and also a Moran number because the ratio is a prime number: 886537 = 20390351 / (2 + 0 + 3 + 9 + 0 + 3 + 5 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20390353) 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, 443246 + ... + 443291.

It is an arithmetic number, because the mean of its divisors is an integer number (5319228).

Almost surely, 2^20390351 is an apocalyptic number.

20390351 is a deficient number, since it is larger than the sum of its proper divisors (886561).

20390351 is an equidigital number, since it uses as much as digits as its factorization.

20390351 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 886560.

The product of its (nonzero) digits is 810, while the sum is 23.

The square root of 20390351 is about 4515.5676276632. The cubic root of 20390351 is about 273.1963549565.

Adding to 20390351 its reverse (15309302), we get a palindrome (35699653).

The spelling of 20390351 in words is "twenty million, three hundred ninety thousand, three hundred fifty-one".