21515410545415 has 16 divisors (see below), whose sum is σ = 26682591672576. Its totient is φ = 16637564275200.

The previous prime is 21515410545401. The next prime is 21515410545439. The reversal of 21515410545415 is 51454501451512.

It is not a de Polignac number, because 21515410545415 - 2¹³ = 21515410537223 is a prime.

It is a Duffinian number.

It is a congruent 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, 81233026 + ... + 81497455.

It is an arithmetic number, because the mean of its divisors is an integer number (1667661979536).

Almost surely, 2^{21515410545415} is an apocalyptic number.

21515410545415 is a deficient number, since it is larger than the sum of its proper divisors (5167181127161).

21515410545415 is a wasteful number, since it uses less digits than its factorization.

21515410545415 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162731370.

The product of its (nonzero) digits is 400000, while the sum is 43.

Adding to 21515410545415 its reverse (51454501451512), we get a palindrome (72969911996927).

The spelling of 21515410545415 in words is "twenty-one trillion, five hundred fifteen billion, four hundred ten million, five hundred forty-five thousand, four hundred fifteen".