20021553 has 16 divisors (see below), whose sum is σ = 29760960. Its totient is φ = 13303008.

The previous prime is 20021549. The next prime is 20021623. The reversal of 20021553 is 35512002.

It is a happy number.

20021553 is nontrivially palindromic in base 16.

It is not a de Polignac number, because 20021553 - 2² = 20021549 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20021153) 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, 8301 + ... + 10437.

It is an arithmetic number, because the mean of its divisors is an integer number (1860060).

Almost surely, 2^20021553 is an apocalyptic number.

It is an amenable number.

20021553 is a deficient number, since it is larger than the sum of its proper divisors (9739407).

20021553 is a wasteful number, since it uses less digits than its factorization.

20021553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2493 (or 2487 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 18.

The square root of 20021553 is about 4474.5450048022. The cubic root of 20021553 is about 271.5392330593.

Adding to 20021553 its reverse (35512002), we get a palindrome (55533555).

The spelling of 20021553 in words is "twenty million, twenty-one thousand, five hundred fifty-three".