1253320021 has 4 divisors (see below), whose sum is σ = 1283888844. Its totient is φ = 1222751200.

The previous prime is 1253320007. The next prime is 1253320031. The reversal of 1253320021 is 1200233521.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1200233521 = 277 ⋅4332973.

It can be written as a sum of positive squares in 2 ways, for example, as 39564100 + 1213755921 = 6290^2 + 34839^2 .

It is not a de Polignac number, because 1253320021 - 2⁵ = 1253319989 is a prime.

It is a super-2 number, since 2×1253320021² = 3141622150078880882, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1253320031) 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, 15284350 + ... + 15284431.

It is an arithmetic number, because the mean of its divisors is an integer number (320972211).

Almost surely, 2^1253320021 is an apocalyptic number.

It is an amenable number.

1253320021 is a deficient number, since it is larger than the sum of its proper divisors (30568823).

1253320021 is an equidigital number, since it uses as much as digits as its factorization.

1253320021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30568822.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 1253320021 is about 35402.2601114675. The cubic root of 1253320021 is about 1078.1702043649.

Adding to 1253320021 its reverse (1200233521), we get a palindrome (2453553542).

The spelling of 1253320021 in words is "one billion, two hundred fifty-three million, three hundred twenty thousand, twenty-one".