21006254 has 12 divisors (see below), whose sum is σ = 33472824. Its totient is φ = 9885024.

The previous prime is 21006247. The next prime is 21006257. The reversal of 21006254 is 45260012.

It is a happy number.

It is a super-2 number, since 2×21006254² = 882525414225032, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21006257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17594 + ... + 18749.

It is an arithmetic number, because the mean of its divisors is an integer number (2789402).

Almost surely, 2^21006254 is an apocalyptic number.

21006254 is a deficient number, since it is larger than the sum of its proper divisors (12466570).

21006254 is a wasteful number, since it uses less digits than its factorization.

21006254 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36379 (or 36362 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 21006254 is about 4583.2580115023. The cubic root of 21006254 is about 275.9198027163.

Adding to 21006254 its reverse (45260012), we get a palindrome (66266266).

The spelling of 21006254 in words is "twenty-one million, six thousand, two hundred fifty-four".