21552404 has 6 divisors (see below), whose sum is σ = 37716714. Its totient is φ = 10776200.

The previous prime is 21552383. The next prime is 21552437. The reversal of 21552404 is 40425512.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 21252100 + 300304 = 4610^2 + 548^2 .

It is a super-2 number, since 2×21552404² = 929012236358432, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21552404.

It is a congruent number.

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 as a sum of consecutive naturals, namely, 2694047 + ... + 2694054.

It is an arithmetic number, because the mean of its divisors is an integer number (6286119).

Almost surely, 2^21552404 is an apocalyptic number.

It is an amenable number.

21552404 is a deficient number, since it is larger than the sum of its proper divisors (16164310).

21552404 is a wasteful number, since it uses less digits than its factorization.

21552404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5388105 (or 5388103 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 23.

The square root of 21552404 is about 4642.4566772346. The cubic root of 21552404 is about 278.2906230455.

Adding to 21552404 its reverse (40425512), we get a palindrome (61977916).

The spelling of 21552404 in words is "twenty-one million, five hundred fifty-two thousand, four hundred four".