20421255 has 8 divisors (see below), whose sum is σ = 32674032. Its totient is φ = 10891328.

The previous prime is 20421253. The next prime is 20421277. The reversal of 20421255 is 55212402.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20421255 - 2¹ = 20421253 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20421251) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 680694 + ... + 680723.

It is an arithmetic number, because the mean of its divisors is an integer number (4084254).

Almost surely, 2^20421255 is an apocalyptic number.

20421255 is a deficient number, since it is larger than the sum of its proper divisors (12252777).

20421255 is a wasteful number, since it uses less digits than its factorization.

20421255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1361425.

The product of its (nonzero) digits is 800, while the sum is 21.

The square root of 20421255 is about 4518.9882717263. The cubic root of 20421255 is about 273.3343058000.

Adding to 20421255 its reverse (55212402), we get a palindrome (75633657).

The spelling of 20421255 in words is "twenty million, four hundred twenty-one thousand, two hundred fifty-five".