21000342515 has 32 divisors (see below), whose sum is σ = 26733464640. Its totient is φ = 15792537600.

The previous prime is 21000342511. The next prime is 21000342521. The reversal of 21000342515 is 51524300012.

It is not a de Polignac number, because 21000342515 - 2² = 21000342511 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21000342511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6859085 + ... + 6862145.

It is an arithmetic number, because the mean of its divisors is an integer number (835420770).

Almost surely, 2^21000342515 is an apocalyptic number.

21000342515 is a deficient number, since it is larger than the sum of its proper divisors (5733122125).

21000342515 is a wasteful number, since it uses less digits than its factorization.

21000342515 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3623.

The product of its (nonzero) digits is 1200, while the sum is 23.

Adding to 21000342515 its reverse (51524300012), we get a palindrome (72524642527).

The spelling of 21000342515 in words is "twenty-one billion, three hundred forty-two thousand, five hundred fifteen".