21355012400 has 120 divisors (see below), whose sum is σ = 56685684384. Its totient is φ = 7689932800.

The previous prime is 21355012397. The next prime is 21355012403. The reversal of 21355012400 is 421055312.

It is an interprime number because it is at equal distance from previous prime (21355012397) and next prime (21355012403).

It is a Harshad number since it is a multiple of its sum of digits (23).

It is not an unprimeable number, because it can be changed into a prime (21355012403) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 88130 + ... + 224670.

Almost surely, 2^21355012400 is an apocalyptic number.

21355012400 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 21355012400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28342842192).

21355012400 is an abundant number, since it is smaller than the sum of its proper divisors (35330671984).

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

21355012400 is a wasteful number, since it uses less digits than its factorization.

21355012400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136599 (or 136588 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 23.

Adding to 21355012400 its reverse (421055312), we get a palindrome (21776067712).

The spelling of 21355012400 in words is "twenty-one billion, three hundred fifty-five million, twelve thousand, four hundred".