1228038991391 has 4 divisors (see below), whose sum is σ = 1228682957112. Its totient is φ = 1227395025672.

The previous prime is 1228038991367. The next prime is 1228038991409. The reversal of 1228038991391 is 1931998308221.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1228038991391 - 2⁶ = 1228038991327 is a prime.

It is a super-2 number, since 2×1228038991391² (a number of 25 digits) 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 (1228038991321) 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, 321980000 + ... + 321983813.

It is an arithmetic number, because the mean of its divisors is an integer number (307170739278).

Almost surely, 2^{1228038991391} is an apocalyptic number.

1228038991391 is a deficient number, since it is larger than the sum of its proper divisors (643965721).

1228038991391 is an equidigital number, since it uses as much as digits as its factorization.

1228038991391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643965720.

The product of its (nonzero) digits is 1679616, while the sum is 56.

The spelling of 1228038991391 in words is "one trillion, two hundred twenty-eight billion, thirty-eight million, nine hundred ninety-one thousand, three hundred ninety-one".