1991201523 has 8 divisors (see below), whose sum is σ = 2656891536. Its totient is φ = 1326489600.

The previous prime is 1991201521. The next prime is 1991201543. The reversal of 1991201523 is 3251021991.

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

It is not a de Polignac number, because 1991201523 - 2¹ = 1991201521 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1991201521) 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, 239758 + ... + 247923.

It is an arithmetic number, because the mean of its divisors is an integer number (332111442).

Almost surely, 2^1991201523 is an apocalyptic number.

1991201523 is a deficient number, since it is larger than the sum of its proper divisors (665690013).

1991201523 is a wasteful number, since it uses less digits than its factorization.

1991201523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 489045.

The product of its (nonzero) digits is 4860, while the sum is 33.

The square root of 1991201523 is about 44622.8811597817. The cubic root of 1991201523 is about 1258.0707695651.

The spelling of 1991201523 in words is "one billion, nine hundred ninety-one million, two hundred one thousand, five hundred twenty-three".