20421147 has 16 divisors (see below), whose sum is σ = 27666432. Its totient is φ = 13397280.

The previous prime is 20421103. The next prime is 20421179. The reversal of 20421147 is 74112402.

It is a happy number.

It is not a de Polignac number, because 20421147 - 2⁸ = 20420891 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20421187) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 89848 + ... + 90074.

It is an arithmetic number, because the mean of its divisors is an integer number (1729152).

Almost surely, 2^20421147 is an apocalyptic number.

20421147 is a deficient number, since it is larger than the sum of its proper divisors (7245285).

20421147 is a wasteful number, since it uses less digits than its factorization.

20421147 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 578.

The product of its (nonzero) digits is 448, while the sum is 21.

The square root of 20421147 is about 4518.9763221331. The cubic root of 20421147 is about 273.3338239465. Note that the first 3 decimals are identical.

Adding to 20421147 its reverse (74112402), we get a palindrome (94533549).

The spelling of 20421147 in words is "twenty million, four hundred twenty-one thousand, one hundred forty-seven".