21694408128 has 168 divisors, whose sum is σ = 65365810848. Its totient is φ = 6865993728.

The previous prime is 21694408123. The next prime is 21694408133. The reversal of 21694408128 is 82180449612.

21694408128 is a `hidden beast` number, since 21 + 69 + 440 + 8 + 128 = 666.

It is an interprime number because it is at equal distance from previous prime (21694408123) and next prime (21694408133).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21694408123) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1809000 + ... + 1820952.

Almost surely, 2^21694408128 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 21694408128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32682905424).

21694408128 is an abundant number, since it is smaller than the sum of its proper divisors (43671402720).

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

21694408128 is a wasteful number, since it uses less digits than its factorization.

21694408128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12131 (or 12118 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 45.

The spelling of 21694408128 in words is "twenty-one billion, six hundred ninety-four million, four hundred eight thousand, one hundred twenty-eight".