21420521100 has 162 divisors, whose sum is σ = 73800463100. Its totient is φ = 5192827200.

The previous prime is 21420521071. The next prime is 21420521107. The reversal of 21420521100 is 112502412.

21420521100 is a `hidden beast` number, since 2 + 1 + 42 + 0 + 521 + 100 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21420521107) by changing a digit.

It is a polite number, since it can be written in 53 ways as a sum of consecutive naturals, for example, 10551 + ... + 207249.

Almost surely, 2^21420521100 is an apocalyptic number.

21420521100 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 21420521100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36900231550).

21420521100 is an abundant number, since it is smaller than the sum of its proper divisors (52379942000).

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

21420521100 is a wasteful number, since it uses less digits than its factorization.

21420521100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 196741 (or 196720 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The spelling of 21420521100 in words is "twenty-one billion, four hundred twenty million, five hundred twenty-one thousand, one hundred".