16991521371 has 24 divisors (see below), whose sum is σ = 27113448960. Its totient is φ = 10167534000.

The previous prime is 16991521367. The next prime is 16991521373. The reversal of 16991521371 is 17312519961.

16991521371 is a `hidden beast` number, since 1 + 6 + 9 + 91 + 521 + 37 + 1 = 666.

It is not a de Polignac number, because 16991521371 - 2² = 16991521367 is a prime.

It is a super-2 number, since 2×16991521371² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (16991521373) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1078455 + ... + 1094096.

It is an arithmetic number, because the mean of its divisors is an integer number (1129727040).

Almost surely, 2^16991521371 is an apocalyptic number.

16991521371 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

16991521371 is a deficient number, since it is larger than the sum of its proper divisors (10121927589).

16991521371 is a wasteful number, since it uses less digits than its factorization.

16991521371 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2172647 (or 2172644 counting only the distinct ones).

The product of its digits is 102060, while the sum is 45.

The spelling of 16991521371 in words is "sixteen billion, nine hundred ninety-one million, five hundred twenty-one thousand, three hundred seventy-one".