21055567 has 8 divisors (see below), whose sum is σ = 22888656. Its totient is φ = 19252992.

The previous prime is 21055561. The next prime is 21055579. The reversal of 21055567 is 76555012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21055567 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055561) 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, 6178 + ... + 8959.

It is an arithmetic number, because the mean of its divisors is an integer number (2861082).

Almost surely, 2^21055567 is an apocalyptic number.

21055567 is a deficient number, since it is larger than the sum of its proper divisors (1833089).

21055567 is a wasteful number, since it uses less digits than its factorization.

21055567 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15257.

The product of its (nonzero) digits is 10500, while the sum is 31.

The square root of 21055567 is about 4588.6345463547. The cubic root of 21055567 is about 276.1355448136.

The spelling of 21055567 in words is "twenty-one million, fifty-five thousand, five hundred sixty-seven".