21156003072 has 216 divisors, whose sum is σ = 63255815168. Its totient is φ = 6793113600.

The previous prime is 21156003047. The next prime is 21156003091. The reversal of 21156003072 is 27030065112.

It is a happy number.

21156003072 is a `hidden beast` number, since 2 + 1 + 1 + 560 + 0 + 30 + 72 = 666.

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, 19355358 + ... + 19356450.

Almost surely, 2^21156003072 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 21156003072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31627907584).

21156003072 is an abundant number, since it is smaller than the sum of its proper divisors (42099812096).

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

21156003072 is a wasteful number, since it uses less digits than its factorization.

21156003072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1417 (or 1400 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 27.

Adding to 21156003072 its reverse (27030065112), we get a palindrome (48186068184).

The spelling of 21156003072 in words is "twenty-one billion, one hundred fifty-six million, three thousand, seventy-two".