21173550 has 24 divisors (see below), whose sum is σ = 52510776. Its totient is φ = 5646240.

The previous prime is 21173533. The next prime is 21173563. The reversal of 21173550 is 5537112.

It is a self number, because there is not a number n which added to its sum of digits gives 21173550.

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 in 11 ways as a sum of consecutive naturals, for example, 70429 + ... + 70728.

It is an arithmetic number, because the mean of its divisors is an integer number (2187949).

Almost surely, 2^21173550 is an apocalyptic number.

21173550 is an abundant number, since it is smaller than the sum of its proper divisors (31337226).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21173550 is a wasteful number, since it uses less digits than its factorization.

21173550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141172 (or 141167 counting only the distinct ones).

The product of its (nonzero) digits is 1050, while the sum is 24.

The square root of 21173550 is about 4601.4725903780. The cubic root of 21173550 is about 276.6503514516.

The spelling of 21173550 in words is "twenty-one million, one hundred seventy-three thousand, five hundred fifty".