21555455 has 8 divisors (see below), whose sum is σ = 25930800. Its totient is φ = 17201536.

The previous prime is 21555451. The next prime is 21555461. The reversal of 21555455 is 55455512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21555455 - 2² = 21555451 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21555451) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3050 + ... + 7239.

It is an arithmetic number, because the mean of its divisors is an integer number (3241350).

Almost surely, 2^21555455 is an apocalyptic number.

21555455 is a deficient number, since it is larger than the sum of its proper divisors (4375345).

21555455 is a wasteful number, since it uses less digits than its factorization.

21555455 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10713.

The product of its digits is 25000, while the sum is 32.

The square root of 21555455 is about 4642.7852631799. The cubic root of 21555455 is about 278.3037542122.

The spelling of 21555455 in words is "twenty-one million, five hundred fifty-five thousand, four hundred fifty-five".