21555065 has 24 divisors (see below), whose sum is σ = 31417152. Its totient is φ = 13904640.

The previous prime is 21555041. The next prime is 21555067. The reversal of 21555065 is 56055512.

It is not a de Polignac number, because 21555065 - 2⁸ = 21554809 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21555067) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9050 + ... + 11180.

It is an arithmetic number, because the mean of its divisors is an integer number (1309048).

Almost surely, 2^21555065 is an apocalyptic number.

It is an amenable number.

21555065 is a deficient number, since it is larger than the sum of its proper divisors (9862087).

21555065 is a wasteful number, since it uses less digits than its factorization.

21555065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2177 (or 2160 counting only the distinct ones).

The product of its (nonzero) digits is 7500, while the sum is 29.

The square root of 21555065 is about 4642.7432623396. The cubic root of 21555065 is about 278.3020757644.

The spelling of 21555065 in words is "twenty-one million, five hundred fifty-five thousand, sixty-five".