21001421400 has 96 divisors (see below), whose sum is σ = 65435253840. Its totient is φ = 5571919360.

The previous prime is 21001421377. The next prime is 21001421429. The reversal of 21001421400 is 412410012.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21001421400.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 29362 + ... + 207038.

Almost surely, 2^21001421400 is an apocalyptic number.

21001421400 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 21001421400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32717626920).

21001421400 is an abundant number, since it is smaller than the sum of its proper divisors (44433832440).

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

21001421400 is a wasteful number, since it uses less digits than its factorization.

21001421400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 177893 (or 177884 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21001421400 its reverse (412410012), we get a palindrome (21413831412).

The spelling of 21001421400 in words is "twenty-one billion, one million, four hundred twenty-one thousand, four hundred".