21083507172 has 144 divisors (see below), whose sum is σ = 68022794112. Its totient is φ = 5560462080.

The previous prime is 21083507167. The next prime is 21083507183. The reversal of 21083507172 is 27170538012.

21083507172 is a `hidden beast` number, since 2 + 1 + 0 + 83 + 507 + 1 + 72 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 30729 + ... + 207632.

Almost surely, 2^21083507172 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21083507172, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34011397056).

21083507172 is an abundant number, since it is smaller than the sum of its proper divisors (46939286940).

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

21083507172 is a wasteful number, since it uses less digits than its factorization.

21083507172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238400 (or 238386 counting only the distinct ones).

The product of its (nonzero) digits is 23520, while the sum is 36.

The spelling of 21083507172 in words is "twenty-one billion, eighty-three million, five hundred seven thousand, one hundred seventy-two".