21497880291 has 4 divisors (see below), whose sum is σ = 28663840392. Its totient is φ = 14331920192.

The previous prime is 21497880259. The next prime is 21497880301. The reversal of 21497880291 is 19208879412.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21497880291 - 2⁵ = 21497880259 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21497880221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3582980046 + ... + 3582980051.

It is an arithmetic number, because the mean of its divisors is an integer number (7165960098).

Almost surely, 2^21497880291 is an apocalyptic number.

21497880291 is a deficient number, since it is larger than the sum of its proper divisors (7165960101).

21497880291 is an equidigital number, since it uses as much as digits as its factorization.

21497880291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7165960100.

The product of its (nonzero) digits is 580608, while the sum is 51.

The spelling of 21497880291 in words is "twenty-one billion, four hundred ninety-seven million, eight hundred eighty thousand, two hundred ninety-one".