21530243215 has 32 divisors (see below), whose sum is σ = 29521618560. Its totient is φ = 14932905984.

The previous prime is 21530243183. The next prime is 21530243221. The reversal of 21530243215 is 51234203512.

It is a cyclic number.

It is not a de Polignac number, because 21530243215 - 2⁵ = 21530243183 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, 518131 + ... + 558139.

It is an arithmetic number, because the mean of its divisors is an integer number (922550580).

Almost surely, 2^21530243215 is an apocalyptic number.

21530243215 is a deficient number, since it is larger than the sum of its proper divisors (7991375345).

21530243215 is a wasteful number, since it uses less digits than its factorization.

21530243215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40531.

The product of its (nonzero) digits is 7200, while the sum is 28.

Adding to 21530243215 its reverse (51234203512), we get a palindrome (72764446727).

The spelling of 21530243215 in words is "twenty-one billion, five hundred thirty million, two hundred forty-three thousand, two hundred fifteen".