20351491 has 4 divisors (see below), whose sum is σ = 20685184. Its totient is φ = 20017800.

The previous prime is 20351483. The next prime is 20351497. The reversal of 20351491 is 19415302.

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 20351491 - 2³ = 20351483 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20351497) 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, 166755 + ... + 166876.

It is an arithmetic number, because the mean of its divisors is an integer number (5171296).

Almost surely, 2^20351491 is an apocalyptic number.

20351491 is a deficient number, since it is larger than the sum of its proper divisors (333693).

20351491 is an equidigital number, since it uses as much as digits as its factorization.

20351491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333692.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 20351491 is about 4511.2626835510. The cubic root of 20351491 is about 273.0226917409.

Adding to 20351491 its reverse (19415302), we get a palindrome (39766793).

The spelling of 20351491 in words is "twenty million, three hundred fifty-one thousand, four hundred ninety-one".