21001373215 has 32 divisors (see below), whose sum is σ = 27535080384. Its totient is φ = 15314165760.

The previous prime is 21001373203. The next prime is 21001373251. The reversal of 21001373215 is 51237310012.

It is a happy number.

It is not a de Polignac number, because 21001373215 - 2³³ = 12411438623 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21001373215.

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 455452 + ... + 499438.

It is an arithmetic number, because the mean of its divisors is an integer number (860471262).

Almost surely, 2^21001373215 is an apocalyptic number.

21001373215 is a deficient number, since it is larger than the sum of its proper divisors (6533707169).

21001373215 is a wasteful number, since it uses less digits than its factorization.

21001373215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44187.

The product of its (nonzero) digits is 1260, while the sum is 25.

Adding to 21001373215 its reverse (51237310012), we get a palindrome (72238683227).

The spelling of 21001373215 in words is "twenty-one billion, one million, three hundred seventy-three thousand, two hundred fifteen".