21353543640 has 192 divisors, whose sum is σ = 81531908640. Its totient is φ = 4778403840.

The previous prime is 21353543633. The next prime is 21353543641. The reversal of 21353543640 is 4634535312.

21353543640 is a `hidden beast` number, since 2 + 1 + 3 + 5 + 3 + 5 + 4 + 3 + 640 = 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 = 21353543595 and 21353543604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21353543641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 155917 + ... + 258876.

Almost surely, 2^21353543640 is an apocalyptic number.

21353543640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21353543640 is an abundant number, since it is smaller than the sum of its proper divisors (60178365000).

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

21353543640 is a wasteful number, since it uses less digits than its factorization.

21353543640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 414834 (or 414827 counting only the distinct ones).

The product of its (nonzero) digits is 129600, while the sum is 36.

The spelling of 21353543640 in words is "twenty-one billion, three hundred fifty-three million, five hundred forty-three thousand, six hundred forty".