21125010515 has 16 divisors (see below), whose sum is σ = 29030956032. Its totient is φ = 14455965024.

The previous prime is 21125010497. The next prime is 21125010539. The reversal of 21125010515 is 51501052112.

It is a cyclic number.

It is not a de Polignac number, because 21125010515 - 2¹⁶ = 21124944979 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 602639 + ... + 636728.

It is an arithmetic number, because the mean of its divisors is an integer number (1814434752).

Almost surely, 2^21125010515 is an apocalyptic number.

21125010515 is a deficient number, since it is larger than the sum of its proper divisors (7905945517).

21125010515 is a wasteful number, since it uses less digits than its factorization.

21125010515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1239866.

The product of its (nonzero) digits is 500, while the sum is 23.

Adding to 21125010515 its reverse (51501052112), we get a palindrome (72626062627).

The spelling of 21125010515 in words is "twenty-one billion, one hundred twenty-five million, ten thousand, five hundred fifteen".