20397439 has 4 divisors (see below), whose sum is σ = 20426224. Its totient is φ = 20368656.

The previous prime is 20397427. The next prime is 20397479. The reversal of 20397439 is 93479302.

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-20397439 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20397398 and 20397407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20397409) 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, 13302 + ... + 14755.

It is an arithmetic number, because the mean of its divisors is an integer number (5106556).

Almost surely, 2^20397439 is an apocalyptic number.

20397439 is a deficient number, since it is larger than the sum of its proper divisors (28785).

20397439 is an equidigital number, since it uses as much as digits as its factorization.

20397439 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28784.

The product of its (nonzero) digits is 40824, while the sum is 37.

The square root of 20397439 is about 4516.3523998909. The cubic root of 20397439 is about 273.2280070425.

The spelling of 20397439 in words is "twenty million, three hundred ninety-seven thousand, four hundred thirty-nine".