21006123400 has 48 divisors (see below), whose sum is σ = 49162746240. Its totient is φ = 8346792000.

The previous prime is 21006123377. The next prime is 21006123409. The reversal of 21006123400 is 432160012.

It is not an unprimeable number, because it can be changed into a prime (21006123409) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 317584 + ... + 377983.

It is an arithmetic number, because the mean of its divisors is an integer number (1024223880).

Almost surely, 2^21006123400 is an apocalyptic number.

21006123400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21006123400 is an abundant number, since it is smaller than the sum of its proper divisors (28156622840).

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

21006123400 is a wasteful number, since it uses less digits than its factorization.

21006123400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 695734 (or 695725 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 19.

Adding to 21006123400 its reverse (432160012), we get a palindrome (21438283412).

It can be divided in two parts, 2100612 and 3400, that added together give a palindrome (2104012).

The spelling of 21006123400 in words is "twenty-one billion, six million, one hundred twenty-three thousand, four hundred".