21390193440 has 1152 divisors, whose sum is σ = 96613171200. Its totient is φ = 4267468800.

The previous prime is 21390193417. The next prime is 21390193457. The reversal of 21390193440 is 4439109312.

21390193440 is a `hidden beast` number, since 21 + 3 + 9 + 0 + 193 + 440 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 21390193395 and 21390193404.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 168426657 + ... + 168426783.

It is an arithmetic number, because the mean of its divisors is an integer number (83865600).

Almost surely, 2^21390193440 is an apocalyptic number.

21390193440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21390193440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48306585600).

21390193440 is an abundant number, since it is smaller than the sum of its proper divisors (75222977760).

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

21390193440 is a wasteful number, since it uses less digits than its factorization.

21390193440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211 (or 186 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The spelling of 21390193440 in words is "twenty-one billion, three hundred ninety million, one hundred ninety-three thousand, four hundred forty".