1243637641 has 4 divisors (see below), whose sum is σ = 1244752132. Its totient is φ = 1242523152.

The previous prime is 1243637597. The next prime is 1243637651. The reversal of 1243637641 is 1467363421.

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 165894400 + 1077743241 = 12880^2 + 32829^2 .

It is a cyclic number.

It is not a de Polignac number, because 1243637641 - 2²⁵ = 1210083209 is a prime.

It is a super-2 number, since 2×1243637641² = 3093269164224089762, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1243637641.

It is not an unprimeable number, because it can be changed into a prime (1243637651) 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, 555570 + ... + 557803.

It is an arithmetic number, because the mean of its divisors is an integer number (311188033).

Almost surely, 2^1243637641 is an apocalyptic number.

It is an amenable number.

1243637641 is a deficient number, since it is larger than the sum of its proper divisors (1114491).

1243637641 is a wasteful number, since it uses less digits than its factorization.

1243637641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1114490.

The product of its digits is 72576, while the sum is 37.

The square root of 1243637641 is about 35265.2469295197. The cubic root of 1243637641 is about 1075.3865971350.

The spelling of 1243637641 in words is "one billion, two hundred forty-three million, six hundred thirty-seven thousand, six hundred forty-one".