20542221 has 24 divisors (see below), whose sum is σ = 35403840. Its totient is φ = 11737656.

The previous prime is 20542213. The next prime is 20542253. The reversal of 20542221 is 12224502.

It is not a de Polignac number, because 20542221 - 2³ = 20542213 is a prime.

It is a super-2 number, since 2×20542221² = 843965687225682, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20542194 and 20542203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20542201) 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 23 ways as a sum of consecutive naturals, for example, 6441 + ... + 9086.

It is an arithmetic number, because the mean of its divisors is an integer number (1475160).

Almost surely, 2^20542221 is an apocalyptic number.

20542221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20542221 is a deficient number, since it is larger than the sum of its proper divisors (14861619).

20542221 is a wasteful number, since it uses less digits than its factorization.

20542221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15550 (or 15537 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 20542221 is about 4532.3527003092. The cubic root of 20542221 is about 273.8729453380.

Adding to 20542221 its reverse (12224502), we get a palindrome (32766723).

The spelling of 20542221 in words is "twenty million, five hundred forty-two thousand, two hundred twenty-one".