21215771115015 has 32 divisors (see below), whose sum is σ = 33957436066560. Its totient is φ = 11311011267584.

The previous prime is 21215771114987. The next prime is 21215771115031. The reversal of 21215771115015 is 51051117751212.

It is a cyclic number.

It is not a de Polignac number, because 21215771115015 - 2¹³ = 21215771106823 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 617851927 + ... + 617886263.

It is an arithmetic number, because the mean of its divisors is an integer number (1061169877080).

Almost surely, 2^{21215771115015} is an apocalyptic number.

21215771115015 is a deficient number, since it is larger than the sum of its proper divisors (12741664951545).

21215771115015 is a wasteful number, since it uses less digits than its factorization.

21215771115015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47951.

The product of its (nonzero) digits is 24500, while the sum is 39.

Adding to 21215771115015 its reverse (51051117751212), we get a palindrome (72266888866227).

The spelling of 21215771115015 in words is "twenty-one trillion, two hundred fifteen billion, seven hundred seventy-one million, one hundred fifteen thousand, fifteen".