21097278551616 has 112 divisors (see below), whose sum is σ = 58766597630400. Its totient is φ = 6661297723392.

The previous prime is 21097278551593. The next prime is 21097278551617. The reversal of 21097278551616 is 61615587279012.

It is a happy number.

It is a super-2 number, since 2×21097278551616² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21097278551616.

It is not an unprimeable number, because it can be changed into a prime (21097278551617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24043426 + ... + 24905438.

Almost surely, 2^{21097278551616} 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 21097278551616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29383298815200).

21097278551616 is an abundant number, since it is smaller than the sum of its proper divisors (37669319078784).

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

21097278551616 is a wasteful number, since it uses less digits than its factorization.

21097278551616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 868756 (or 868746 counting only the distinct ones).

The product of its (nonzero) digits is 12700800, while the sum is 60.

The spelling of 21097278551616 in words is "twenty-one trillion, ninety-seven billion, two hundred seventy-eight million, five hundred fifty-one thousand, six hundred sixteen".