2121565640400 has 360 divisors, whose sum is σ = 7710735168864. Its totient is φ = 560146752000.

The previous prime is 2121565640357. The next prime is 2121565640449. The reversal of 2121565640400 is 40465651212.

2121565640400 is a `hidden beast` number, since 2 + 1 + 2 + 1 + 5 + 6 + 5 + 640 + 4 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (360).

It is a super-2 number, since 2×2121565640400² (a number of 25 digits) contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 9709147 + ... + 9925253.

Almost surely, 2^{2121565640400} is an apocalyptic number.

2121565640400 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 2121565640400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3855367584432).

2121565640400 is an abundant number, since it is smaller than the sum of its proper divisors (5589169528464).

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

2121565640400 is a wasteful number, since it uses less digits than its factorization.

2121565640400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 216241 (or 216218 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 36.

The spelling of 2121565640400 in words is "two trillion, one hundred twenty-one billion, five hundred sixty-five million, six hundred forty thousand, four hundred".