20406887 has 4 divisors (see below), whose sum is σ = 20472816. Its totient is φ = 20340960.

The previous prime is 20406833. The next prime is 20406917. The reversal of 20406887 is 78860402.

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 20406887 - 2⁶ = 20406823 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20402887) 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, 32498 + ... + 33119.

It is an arithmetic number, because the mean of its divisors is an integer number (5118204).

Almost surely, 2^20406887 is an apocalyptic number.

20406887 is a deficient number, since it is larger than the sum of its proper divisors (65929).

20406887 is an equidigital number, since it uses as much as digits as its factorization.

20406887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65928.

The product of its (nonzero) digits is 21504, while the sum is 35.

The square root of 20406887 is about 4517.3982556334. The cubic root of 20406887 is about 273.2701865165.

The spelling of 20406887 in words is "twenty million, four hundred six thousand, eight hundred eighty-seven".