21554165 has 16 divisors (see below), whose sum is σ = 26725248. Its totient is φ = 16675776.

The previous prime is 21554161. The next prime is 21554173. The reversal of 21554165 is 56145512.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21554165 - 2² = 21554161 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21554161) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 48434 + ... + 48876.

It is an arithmetic number, because the mean of its divisors is an integer number (1670328).

Almost surely, 2^21554165 is an apocalyptic number.

It is an amenable number.

21554165 is a deficient number, since it is larger than the sum of its proper divisors (5171083).

21554165 is a wasteful number, since it uses less digits than its factorization.

21554165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 748.

The product of its digits is 6000, while the sum is 29.

The square root of 21554165 is about 4642.6463358735. The cubic root of 21554165 is about 278.2982023460.

Adding to 21554165 its reverse (56145512), we get a palindrome (77699677).

The spelling of 21554165 in words is "twenty-one million, five hundred fifty-four thousand, one hundred sixty-five".