21520145615 has 16 divisors (see below), whose sum is σ = 27064670400. Its totient is φ = 16395658752.

The previous prime is 21520145611. The next prime is 21520145627. The reversal of 21520145615 is 51654102512.

It is a cyclic number.

It is not a de Polignac number, because 21520145615 - 2² = 21520145611 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21520145611) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 382250 + ... + 434919.

It is an arithmetic number, because the mean of its divisors is an integer number (1691541900).

Almost surely, 2^21520145615 is an apocalyptic number.

21520145615 is a deficient number, since it is larger than the sum of its proper divisors (5544524785).

21520145615 is a wasteful number, since it uses less digits than its factorization.

21520145615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 817426.

The product of its (nonzero) digits is 12000, while the sum is 32.

The spelling of 21520145615 in words is "twenty-one billion, five hundred twenty million, one hundred forty-five thousand, six hundred fifteen".