21405320645760 has 384 divisors, whose sum is σ = 75843308136960. Its totient is φ = 5559652270080.

The previous prime is 21405320645717. The next prime is 21405320645803. The reversal of 21405320645760 is 6754602350412.

21405320645760 is a `hidden beast` number, since 2 + 1 + 4 + 0 + 53 + 20 + 6 + 4 + 576 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (21405320645717) and next prime (21405320645803).

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 143274459 + ... + 143423781.

It is an arithmetic number, because the mean of its divisors is an integer number (197508614940).

Almost surely, 2^{21405320645760} is an apocalyptic number.

21405320645760 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 21405320645760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37921654068480).

21405320645760 is an abundant number, since it is smaller than the sum of its proper divisors (54437987491200).

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

21405320645760 is a wasteful number, since it uses less digits than its factorization.

21405320645760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149996 (or 149981 counting only the distinct ones).

The product of its (nonzero) digits is 1209600, while the sum is 45.

The spelling of 21405320645760 in words is "twenty-one trillion, four hundred five billion, three hundred twenty million, six hundred forty-five thousand, seven hundred sixty".