21253363665400 has 384 divisors, whose sum is σ = 53739417600000. Its totient is φ = 7795782973440.

The previous prime is 21253363665353. The next prime is 21253363665409. The reversal of 21253363665400 is 456636335212.

It is a Harshad number since it is a multiple of its sum of digits (46).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253363665409) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 3220691301 + ... + 3220697899.

It is an arithmetic number, because the mean of its divisors is an integer number (139946400000).

Almost surely, 2^{21253363665400} is an apocalyptic number.

21253363665400 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 21253363665400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26869708800000).

21253363665400 is an abundant number, since it is smaller than the sum of its proper divisors (32486053934600).

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

21253363665400 is a wasteful number, since it uses less digits than its factorization.

21253363665400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6951 (or 6942 counting only the distinct ones).

The product of its (nonzero) digits is 2332800, while the sum is 46.

The spelling of 21253363665400 in words is "twenty-one trillion, two hundred fifty-three billion, three hundred sixty-three million, six hundred sixty-five thousand, four hundred".