21345555 has 32 divisors (see below), whose sum is σ = 42582528. Its totient is φ = 8870400.

The previous prime is 21345539. The next prime is 21345589. The reversal of 21345555 is 55554312.

It is a happy number.

It is not a de Polignac number, because 21345555 - 2⁴ = 21345539 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8086 + ... + 10395.

It is an arithmetic number, because the mean of its divisors is an integer number (1330704).

Almost surely, 2^21345555 is an apocalyptic number.

21345555 is a deficient number, since it is larger than the sum of its proper divisors (21236973).

21345555 is a wasteful number, since it uses less digits than its factorization.

21345555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18507.

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

The square root of 21345555 is about 4620.1249983090. The cubic root of 21345555 is about 277.3974623194.

Adding to 21345555 its reverse (55554312), we get a palindrome (76899867).

The spelling of 21345555 in words is "twenty-one million, three hundred forty-five thousand, five hundred fifty-five".