20678491 has 4 divisors (see below), whose sum is σ = 20961832. Its totient is φ = 20395152.

The previous prime is 20678453. The next prime is 20678513. The reversal of 20678491 is 19487602.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20678491 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20678491.

It is not an unprimeable number, because it can be changed into a prime (20678401) 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, 141561 + ... + 141706.

It is an arithmetic number, because the mean of its divisors is an integer number (5240458).

Almost surely, 2^20678491 is an apocalyptic number.

20678491 is a deficient number, since it is larger than the sum of its proper divisors (283341).

20678491 is an equidigital number, since it uses as much as digits as its factorization.

20678491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283340.

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 20678491 is about 4547.3608829738. The cubic root of 20678491 is about 274.4772039999.

The spelling of 20678491 in words is "twenty million, six hundred seventy-eight thousand, four hundred ninety-one".