21404212440 has 128 divisors (see below), whose sum is σ = 73219930560. Its totient is φ = 4958797824.

The previous prime is 21404212421. The next prime is 21404212471. The reversal of 21404212440 is 4421240412.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21404212440.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 377029 + ... + 430068.

Almost surely, 2^21404212440 is an apocalyptic number.

21404212440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21404212440 is an abundant number, since it is smaller than the sum of its proper divisors (51815718120).

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

21404212440 is a wasteful number, since it uses less digits than its factorization.

21404212440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 807141 (or 807137 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 24.

Adding to 21404212440 its reverse (4421240412), we get a palindrome (25825452852).

The spelling of 21404212440 in words is "twenty-one billion, four hundred four million, two hundred twelve thousand, four hundred forty".