21424155 has 16 divisors (see below), whose sum is σ = 35769600. Its totient is φ = 10929248.

The previous prime is 21424129. The next prime is 21424159. The reversal of 21424155 is 55142412.

It is a cyclic number.

It is not a de Polignac number, because 21424155 - 2⁷ = 21424027 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21424159) 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, 30705 + ... + 31394.

It is an arithmetic number, because the mean of its divisors is an integer number (2235600).

Almost surely, 2^21424155 is an apocalyptic number.

21424155 is a deficient number, since it is larger than the sum of its proper divisors (14345445).

21424155 is a wasteful number, since it uses less digits than its factorization.

21424155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62130.

The product of its digits is 1600, while the sum is 24.

The square root of 21424155 is about 4628.6234454749. The cubic root of 21424155 is about 277.7375289536.

Adding to 21424155 its reverse (55142412), we get a palindrome (76566567).

The spelling of 21424155 in words is "twenty-one million, four hundred twenty-four thousand, one hundred fifty-five".