191221680 has 160 divisors (see below), whose sum is σ = 643958784. Its totient is φ = 46660608.

The previous prime is 191221669. The next prime is 191221699. The reversal of 191221680 is 86122191.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 520857 + ... + 521223.

Almost surely, 2^191221680 is an apocalyptic number.

191221680 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 191221680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (321979392).

191221680 is an abundant number, since it is smaller than the sum of its proper divisors (452737104).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

191221680 is a wasteful number, since it uses less digits than its factorization.

191221680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 563 (or 557 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 30.

The square root of 191221680 is about 13828.2927362708. The cubic root of 191221680 is about 576.1192365037.

It can be divided in two parts, 19122 and 1680, that added together give a palindrome (20802).

The spelling of 191221680 in words is "one hundred ninety-one million, two hundred twenty-one thousand, six hundred eighty".