21001550100 has 144 divisors (see below), whose sum is σ = 64550618496. Its totient is φ = 5253632000.

The previous prime is 21001550099. The next prime is 21001550111. The reversal of 21001550100 is 105510012.

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 21001550100.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1579480 + ... + 1592720.

It is an arithmetic number, because the mean of its divisors is an integer number (448268184).

Almost surely, 2^21001550100 is an apocalyptic number.

21001550100 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 21001550100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32275309248).

21001550100 is an abundant number, since it is smaller than the sum of its proper divisors (43549068396).

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

21001550100 is a wasteful number, since it uses less digits than its factorization.

21001550100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13586 (or 13579 counting only the distinct ones).

The product of its (nonzero) digits is 50, while the sum is 15.

The spelling of 21001550100 in words is "twenty-one billion, one million, five hundred fifty thousand, one hundred".