21121423400 has 192 divisors, whose sum is σ = 61405534080. Its totient is φ = 6563865600.

The previous prime is 21121423327. The next prime is 21121423447. The reversal of 21121423400 is 432412112.

It is a super-2 number, since 2×21121423400² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

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, 5742362 + ... + 5746038.

It is an arithmetic number, because the mean of its divisors is an integer number (319820490).

Almost surely, 2^21121423400 is an apocalyptic number.

21121423400 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 21121423400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30702767040).

21121423400 is an abundant number, since it is smaller than the sum of its proper divisors (40284110680).

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

21121423400 is a wasteful number, since it uses less digits than its factorization.

21121423400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4084 (or 4075 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

Adding to 21121423400 its reverse (432412112), we get a palindrome (21553835512).

The spelling of 21121423400 in words is "twenty-one billion, one hundred twenty-one million, four hundred twenty-three thousand, four hundred".