20261491 has 4 divisors (see below), whose sum is σ = 20307672. Its totient is φ = 20215312.

The previous prime is 20261431. The next prime is 20261497. The reversal of 20261491 is 19416202.

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 20261491 - 2⁷ = 20261363 is a prime.

It is a super-3 number, since 3×20261491³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20261497) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22426 + ... + 23311.

It is an arithmetic number, because the mean of its divisors is an integer number (5076918).

Almost surely, 2^20261491 is an apocalyptic number.

20261491 is a deficient number, since it is larger than the sum of its proper divisors (46181).

20261491 is an equidigital number, since it uses as much as digits as its factorization.

20261491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46180.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 20261491 is about 4501.2765967001. The cubic root of 20261491 is about 272.6196360467.

Adding to 20261491 its reverse (19416202), we get a palindrome (39677693).

The spelling of 20261491 in words is "twenty million, two hundred sixty-one thousand, four hundred ninety-one".