21005246407 has 8 divisors (see below), whose sum is σ = 21221222400. Its totient is φ = 20790060984.

The previous prime is 21005246399. The next prime is 21005246417. The reversal of 21005246407 is 70464250012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21005246407 - 2³ = 21005246399 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21005246417) 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 7 ways as a sum of consecutive naturals, for example, 144157 + ... + 250582.

It is an arithmetic number, because the mean of its divisors is an integer number (2652652800).

Almost surely, 2^21005246407 is an apocalyptic number.

21005246407 is a deficient number, since it is larger than the sum of its proper divisors (215975993).

21005246407 is a wasteful number, since it uses less digits than its factorization.

21005246407 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 395285.

The product of its (nonzero) digits is 13440, while the sum is 31.

Adding to 21005246407 its reverse (70464250012), we get a palindrome (91469496419).

The spelling of 21005246407 in words is "twenty-one billion, five million, two hundred forty-six thousand, four hundred seven".