21404004550 has 24 divisors (see below), whose sum is σ = 39837294000. Its totient is φ = 8556043680.

The previous prime is 21404004511. The next prime is 21404004569. The reversal of 21404004550 is 5540040412.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 60730 + ... + 215629.

It is an arithmetic number, because the mean of its divisors is an integer number (1659887250).

Almost surely, 2^21404004550 is an apocalyptic number.

21404004550 is a deficient number, since it is larger than the sum of its proper divisors (18433289450).

21404004550 is a wasteful number, since it uses less digits than its factorization.

21404004550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 277920 (or 277915 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 25.

Adding to 21404004550 its reverse (5540040412), we get a palindrome (26944044962).

The spelling of 21404004550 in words is "twenty-one billion, four hundred four million, four thousand, five hundred fifty".