1691228391 has 8 divisors (see below), whose sum is σ = 2387616624. Its totient is φ = 1061162880.

The previous prime is 1691228377. The next prime is 1691228417. The reversal of 1691228391 is 1938221961.

1691228391 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1691228391 - 2⁵ = 1691228359 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1691228321) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16580620 + ... + 16580721.

It is an arithmetic number, because the mean of its divisors is an integer number (298452078).

Almost surely, 2^1691228391 is an apocalyptic number.

1691228391 is a deficient number, since it is larger than the sum of its proper divisors (696388233).

1691228391 is a wasteful number, since it uses less digits than its factorization.

1691228391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33161361.

The product of its digits is 46656, while the sum is 42.

The square root of 1691228391 is about 41124.5473044993. The cubic root of 1691228391 is about 1191.4269516965.

The spelling of 1691228391 in words is "one billion, six hundred ninety-one million, two hundred twenty-eight thousand, three hundred ninety-one".