21618057815 has 8 divisors (see below), whose sum is σ = 25948719888. Its totient is φ = 17289745920.

The previous prime is 21618057787. The next prime is 21618057841. The reversal of 21618057815 is 51875081612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21618057815 - 2¹⁰ = 21618056791 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 7 ways as a sum of consecutive naturals, for example, 567242 + ... + 604151.

It is an arithmetic number, because the mean of its divisors is an integer number (3243589986).

Almost surely, 2^21618057815 is an apocalyptic number.

21618057815 is a deficient number, since it is larger than the sum of its proper divisors (4330662073).

21618057815 is a wasteful number, since it uses less digits than its factorization.

21618057815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1175089.

The product of its (nonzero) digits is 134400, while the sum is 44.

The spelling of 21618057815 in words is "twenty-one billion, six hundred eighteen million, fifty-seven thousand, eight hundred fifteen".