20400047 has 4 divisors (see below), whose sum is σ = 20734536. Its totient is φ = 20065560.

The previous prime is 20400031. The next prime is 20400049. The reversal of 20400047 is 74000402.

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 20400047 - 2⁴ = 20400031 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20399998 and 20400034.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20400049) 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, 167153 + ... + 167274.

It is an arithmetic number, because the mean of its divisors is an integer number (5183634).

Almost surely, 2^20400047 is an apocalyptic number.

20400047 is a deficient number, since it is larger than the sum of its proper divisors (334489).

20400047 is an equidigital number, since it uses as much as digits as its factorization.

20400047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 334488.

The product of its (nonzero) digits is 224, while the sum is 17.

The square root of 20400047 is about 4516.6411192389. The cubic root of 20400047 is about 273.2396514500.

Adding to 20400047 its reverse (74000402), we get a palindrome (94400449).

The spelling of 20400047 in words is "twenty million, four hundred thousand, forty-seven".