21420153 has 32 divisors (see below), whose sum is σ = 35078400. Its totient is φ = 12849408.

The previous prime is 21420143. The next prime is 21420169. The reversal of 21420153 is 35102412.

It is not a de Polignac number, because 21420153 - 2⁴ = 21420137 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21420103) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9543 + ... + 11571.

It is an arithmetic number, because the mean of its divisors is an integer number (1096200).

Almost surely, 2^21420153 is an apocalyptic number.

21420153 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21420153 is a deficient number, since it is larger than the sum of its proper divisors (13658247).

21420153 is a wasteful number, since it uses less digits than its factorization.

21420153 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2078 (or 2072 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21420153 is about 4628.1911153279. The cubic root of 21420153 is about 277.7202342255.

Adding to 21420153 its reverse (35102412), we get a palindrome (56522565).

The spelling of 21420153 in words is "twenty-one million, four hundred twenty thousand, one hundred fifty-three".