21404123424 has 96 divisors (see below), whose sum is σ = 62480376000. Its totient is φ = 7128801792.

The previous prime is 21404123381. The next prime is 21404123437. The reversal of 21404123424 is 42432140412.

21404123424 is a `hidden beast` number, since 2 + 1 + 404 + 1 + 234 + 24 = 666.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1104087 + ... + 1123305.

It is an arithmetic number, because the mean of its divisors is an integer number (650837250).

Almost surely, 2^21404123424 is an apocalyptic number.

21404123424 is a gapful number since it is divisible by the number (24) 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 21404123424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31240188000).

21404123424 is an abundant number, since it is smaller than the sum of its proper divisors (41076252576).

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

21404123424 is a wasteful number, since it uses less digits than its factorization.

21404123424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20527 (or 20513 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 27.

Adding to 21404123424 its reverse (42432140412), we get a palindrome (63836263836).

The spelling of 21404123424 in words is "twenty-one billion, four hundred four million, one hundred twenty-three thousand, four hundred twenty-four".