21170533 has 2 divisors, whose sum is σ = 21170534. Its totient is φ = 21170532.

The previous prime is 21170521. The next prime is 21170537. The reversal of 21170533 is 33507112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13235044 + 7935489 = 3638^2 + 2817^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21170533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21170537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10585266 + 10585267.

It is an arithmetic number, because the mean of its divisors is an integer number (10585267).

Almost surely, 2^21170533 is an apocalyptic number.

It is an amenable number.

21170533 is a deficient number, since it is larger than the sum of its proper divisors (1).

21170533 is an equidigital number, since it uses as much as digits as its factorization.

21170533 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 630, while the sum is 22.

The square root of 21170533 is about 4601.1447488641. The cubic root of 21170533 is about 276.6372109413.

Adding to 21170533 its reverse (33507112), we get a palindrome (54677645).

The spelling of 21170533 in words is "twenty-one million, one hundred seventy thousand, five hundred thirty-three".