1253643551 has 4 divisors (see below), whose sum is σ = 1255495992. Its totient is φ = 1251791112.

The previous prime is 1253643533. The next prime is 1253643557. The reversal of 1253643551 is 1553463521.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1553463521 = 9323 ⋅166627.

It is a cyclic number.

It is not a de Polignac number, because 1253643551 - 2²² = 1249449247 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 (1253643557) 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, 925205 + ... + 926558.

It is an arithmetic number, because the mean of its divisors is an integer number (313873998).

Almost surely, 2^1253643551 is an apocalyptic number.

1253643551 is a deficient number, since it is larger than the sum of its proper divisors (1852441).

1253643551 is an equidigital number, since it uses as much as digits as its factorization.

1253643551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1852440.

The product of its digits is 54000, while the sum is 35.

The square root of 1253643551 is about 35406.8291576639. The cubic root of 1253643551 is about 1078.2629687534.

The spelling of 1253643551 in words is "one billion, two hundred fifty-three million, six hundred forty-three thousand, five hundred fifty-one".