20645999366400 has 1728 divisors, whose sum is σ = 81005348659200. Its totient is φ = 5130756587520.

The previous prime is 20645999366359. The next prime is 20645999366429. The reversal of 20645999366400 is 466399954602.

20645999366400 is a `hidden beast` number, since 2 + 0 + 6 + 4 + 599 + 9 + 36 + 6 + 4 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1728).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 92582956689 + ... + 92582956911.

Almost surely, 2^{20645999366400} is an apocalyptic number.

20645999366400 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 20645999366400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40502674329600).

20645999366400 is an abundant number, since it is smaller than the sum of its proper divisors (60359349292800).

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

20645999366400 is a wasteful number, since it uses less digits than its factorization.

20645999366400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 613 (or 588 counting only the distinct ones).

The product of its (nonzero) digits is 75582720, while the sum is 63.

The spelling of 20645999366400 in words is "twenty trillion, six hundred forty-five billion, nine hundred ninety-nine million, three hundred sixty-six thousand, four hundred".