20423947 has 4 divisors (see below), whose sum is σ = 21082816. Its totient is φ = 19765080.

The previous prime is 20423941. The next prime is 20423969. The reversal of 20423947 is 74932402.

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 20423947 - 2³ = 20423939 is a prime.

It is a super-2 number, since 2×20423947² = 834275222117618, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 658837 = 20423947 / (2 + 0 + 4 + 2 + 3 + 9 + 4 + 7).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20423941) 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, 329388 + ... + 329449.

It is an arithmetic number, because the mean of its divisors is an integer number (5270704).

Almost surely, 2^20423947 is an apocalyptic number.

20423947 is a deficient number, since it is larger than the sum of its proper divisors (658869).

20423947 is an equidigital number, since it uses as much as digits as its factorization.

20423947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 658868.

The product of its (nonzero) digits is 12096, while the sum is 31.

The square root of 20423947 is about 4519.2861161914. The cubic root of 20423947 is about 273.3463158947.

The spelling of 20423947 in words is "twenty million, four hundred twenty-three thousand, nine hundred forty-seven".