21355554 has 32 divisors (see below), whose sum is σ = 46759680. Its totient is φ = 6448400.

The previous prime is 21355511. The next prime is 21355561. The reversal of 21355554 is 45555312.

It is a happy 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 15 ways as a sum of consecutive naturals, for example, 32077 + ... + 32735.

It is an arithmetic number, because the mean of its divisors is an integer number (1461240).

Almost surely, 2^21355554 is an apocalyptic number.

21355554 is an abundant number, since it is smaller than the sum of its proper divisors (25404126).

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

21355554 is a wasteful number, since it uses less digits than its factorization.

21355554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1166.

The product of its digits is 15000, while the sum is 30.

The square root of 21355554 is about 4621.2069851934. The cubic root of 21355554 is about 277.4407697627.

The spelling of 21355554 in words is "twenty-one million, three hundred fifty-five thousand, five hundred fifty-four".