21515630545 has 32 divisors (see below), whose sum is σ = 26615757600. Its totient is φ = 16691558400.

The previous prime is 21515630519. The next prime is 21515630659. The reversal of 21515630545 is 54503651512.

It is a happy number.

It can be written as a sum of positive squares in 16 ways, for example, as 748514881 + 20767115664 = 27359^2 + 144108^2 .

It is not a de Polignac number, because 21515630545 - 2¹⁹ = 21515106257 is a prime.

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, 5490927 + ... + 5494843.

It is an arithmetic number, because the mean of its divisors is an integer number (831742425).

Almost surely, 2^21515630545 is an apocalyptic number.

It is an amenable number.

21515630545 is a deficient number, since it is larger than the sum of its proper divisors (5100127055).

21515630545 is a wasteful number, since it uses less digits than its factorization.

21515630545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4245.

The product of its (nonzero) digits is 90000, while the sum is 37.

The spelling of 21515630545 in words is "twenty-one billion, five hundred fifteen million, six hundred thirty thousand, five hundred forty-five".