21015330445851 has 16 divisors (see below), whose sum is σ = 32306753255424. Its totient is φ = 11902488038784.

The previous prime is 21015330445847. The next prime is 21015330445853. The reversal of 21015330445851 is 15854403351012.

It is not a de Polignac number, because 21015330445851 - 2² = 21015330445847 is a prime.

It is a super-2 number, since 2×21015330445851² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21015330445853) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4428006571 + ... + 4428011316.

It is an arithmetic number, because the mean of its divisors is an integer number (2019172078464).

Almost surely, 2^{21015330445851} is an apocalyptic number.

21015330445851 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21015330445851 is a deficient number, since it is larger than the sum of its proper divisors (11291422809573).

21015330445851 is a wasteful number, since it uses less digits than its factorization.

21015330445851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8856018010.

The product of its (nonzero) digits is 288000, while the sum is 42.

Adding to 21015330445851 its reverse (15854403351012), we get a palindrome (36869733796863).

The spelling of 21015330445851 in words is "twenty-one trillion, fifteen billion, three hundred thirty million, four hundred forty-five thousand, eight hundred fifty-one".