21491091349 has 96 divisors (see below), whose sum is σ = 29016960000. Its totient is φ = 15905084832.

The previous prime is 21491091343. The next prime is 21491091439. The reversal of 21491091349 is 94319019412.

It is a happy number.

It is not a de Polignac number, because 21491091349 - 2⁷ = 21491091221 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21491091343) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 272039092 + ... + 272039170.

It is an arithmetic number, because the mean of its divisors is an integer number (302260000).

Almost surely, 2^21491091349 is an apocalyptic number.

It is an amenable number.

21491091349 is a deficient number, since it is larger than the sum of its proper divisors (7525868651).

21491091349 is an frugal number, since it uses more digits than its factorization.

21491091349 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 177 (or 118 counting only the distinct ones).

The product of its (nonzero) digits is 69984, while the sum is 43.

The spelling of 21491091349 in words is "twenty-one billion, four hundred ninety-one million, ninety-one thousand, three hundred forty-nine".