21493905207 has 4 divisors (see below), whose sum is σ = 28658540280. Its totient is φ = 14329270136.

The previous prime is 21493905163. The next prime is 21493905221. The reversal of 21493905207 is 70250939412.

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 21493905207 - 2¹⁸ = 21493643063 is a prime.

It is a super-2 number, since 2×21493905207² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21493905227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3582317532 + ... + 3582317537.

It is an arithmetic number, because the mean of its divisors is an integer number (7164635070).

Almost surely, 2^21493905207 is an apocalyptic number.

21493905207 is a deficient number, since it is larger than the sum of its proper divisors (7164635073).

21493905207 is an equidigital number, since it uses as much as digits as its factorization.

21493905207 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7164635072.

The product of its (nonzero) digits is 136080, while the sum is 42.

The spelling of 21493905207 in words is "twenty-one billion, four hundred ninety-three million, nine hundred five thousand, two hundred seven".