21002554 has 16 divisors (see below), whose sum is σ = 32740200. Its totient is φ = 10092544.

The previous prime is 21002549. The next prime is 21002563. The reversal of 21002554 is 45520012.

It can be written as a sum of positive squares in 4 ways, for example, as 18020025 + 2982529 = 4245^2 + 1727^2 .

It is a super-2 number, since 2×21002554² = 882214549045832, which contains 22 as substring.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 14202 + ... + 15610.

Almost surely, 2^21002554 is an apocalyptic number.

21002554 is a deficient number, since it is larger than the sum of its proper divisors (11737646).

21002554 is a wasteful number, since it uses less digits than its factorization.

21002554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1697.

The product of its (nonzero) digits is 400, while the sum is 19.

The square root of 21002554 is about 4582.8543507295. The cubic root of 21002554 is about 275.9036017757.

Adding to 21002554 its reverse (45520012), we get a palindrome (66522566).

The spelling of 21002554 in words is "twenty-one million, two thousand, five hundred fifty-four".