1601388891 has 6 divisors (see below), whose sum is σ = 2313117300. Its totient is φ = 1067592588.

The previous prime is 1601388889. The next prime is 1601388907. The reversal of 1601388891 is 1988831061.

1601388891 is a `hidden beast` number, since 1 + 601 + 38 + 8 + 8 + 9 + 1 = 666.

It is not a de Polignac number, because 1601388891 - 2¹ = 1601388889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1601388821) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 88966041 + ... + 88966058.

It is an arithmetic number, because the mean of its divisors is an integer number (385519550).

Almost surely, 2^1601388891 is an apocalyptic number.

1601388891 is a deficient number, since it is larger than the sum of its proper divisors (711728409).

1601388891 is a wasteful number, since it uses less digits than its factorization.

1601388891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 177932105 (or 177932102 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 45.

The square root of 1601388891 is about 40017.3573715207. The cubic root of 1601388891 is about 1169.9454259007.

The spelling of 1601388891 in words is "one billion, six hundred one million, three hundred eighty-eight thousand, eight hundred ninety-one".