21170153 has 4 divisors (see below), whose sum is σ = 21388500. Its totient is φ = 20951808.

The previous prime is 21170137. The next prime is 21170159. The reversal of 21170153 is 35107112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11102224 + 10067929 = 3332^2 + 3173^2 .

It is a cyclic number.

It is not a de Polignac number, because 21170153 - 2⁴ = 21170137 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21170159) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 109028 + ... + 109221.

It is an arithmetic number, because the mean of its divisors is an integer number (5347125).

Almost surely, 2^21170153 is an apocalyptic number.

It is an amenable number.

21170153 is a deficient number, since it is larger than the sum of its proper divisors (218347).

21170153 is an equidigital number, since it uses as much as digits as its factorization.

21170153 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218346.

The product of its (nonzero) digits is 210, while the sum is 20.

The square root of 21170153 is about 4601.1034546074. The cubic root of 21170153 is about 276.6355557669.

Adding to 21170153 its reverse (35107112), we get a palindrome (56277265).

The spelling of 21170153 in words is "twenty-one million, one hundred seventy thousand, one hundred fifty-three".