1253543021 has 4 divisors (see below), whose sum is σ = 1254268092. Its totient is φ = 1252817952.

The previous prime is 1253542903. The next prime is 1253543041. The reversal of 1253543021 is 1203453521.

It is a happy number.

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 376554025 + 876988996 = 19405^2 + 29614^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1253543021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1253543041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 359936 + ... + 363401.

It is an arithmetic number, because the mean of its divisors is an integer number (313567023).

Almost surely, 2^1253543021 is an apocalyptic number.

It is an amenable number.

1253543021 is a deficient number, since it is larger than the sum of its proper divisors (725071).

1253543021 is an equidigital number, since it uses as much as digits as its factorization.

1253543021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 725070.

The product of its (nonzero) digits is 3600, while the sum is 26.

The square root of 1253543021 is about 35405.4094878170. The cubic root of 1253543021 is about 1078.2341459210.

Adding to 1253543021 its reverse (1203453521), we get a palindrome (2456996542).

The spelling of 1253543021 in words is "one billion, two hundred fifty-three million, five hundred forty-three thousand, twenty-one".