21315371616 has 1080 divisors, whose sum is σ = 85529145240. Its totient is φ = 5173217280.

The previous prime is 21315371587. The next prime is 21315371621. The reversal of 21315371616 is 61617351312.

21315371616 is a `hidden beast` number, since 2 + 1 + 3 + 1 + 5 + 37 + 1 + 616 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 179 ways as a sum of consecutive naturals, for example, 291991356 + ... + 291991428.

It is an arithmetic number, because the mean of its divisors is an integer number (79193653).

Almost surely, 2^21315371616 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21315371616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42764572620).

21315371616 is an abundant number, since it is smaller than the sum of its proper divisors (64213773624).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21315371616 is a wasteful number, since it uses less digits than its factorization.

21315371616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150 (or 115 counting only the distinct ones).

The product of its digits is 22680, while the sum is 36.

The spelling of 21315371616 in words is "twenty-one billion, three hundred fifteen million, three hundred seventy-one thousand, six hundred sixteen".