21240421400 has 48 divisors (see below), whose sum is σ = 53873438040. Its totient is φ = 7723788800.

The previous prime is 21240421381. The next prime is 21240421429. The reversal of 21240421400 is 412404212.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4825169 + ... + 4829568.

Almost surely, 2^21240421400 is an apocalyptic number.

21240421400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21240421400 is an abundant number, since it is smaller than the sum of its proper divisors (32633016640).

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

21240421400 is a wasteful number, since it uses less digits than its factorization.

21240421400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9654764 (or 9654755 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 20.

Adding to 21240421400 its reverse (412404212), we get a palindrome (21652825612).

The spelling of 21240421400 in words is "twenty-one billion, two hundred forty million, four hundred twenty-one thousand, four hundred".