21780412968601 has 9 divisors (see below), whose sum is σ = 25336436761749. Its totient is φ = 18668897399964.

The previous prime is 21780412968571. The next prime is 21780412968667. The reversal of 21780412968601 is 10686921408712.

The square root of 21780412968601 is 4666949.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 21780412968601 - 2²⁵ = 21780379414169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21780412968101) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 32335290 + ... + 33001996.

Almost surely, 2^{21780412968601} is an apocalyptic number.

21780412968601 is the 4666949-th square number.

21780412968601 is the 2333475-th centered octagonal number.

It is an amenable number.

21780412968601 is a deficient number, since it is larger than the sum of its proper divisors (3556023793148).

21780412968601 is an frugal number, since it uses more digits than its factorization.

21780412968601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1333428 (or 666714 counting only the distinct ones).

The product of its (nonzero) digits is 2322432, while the sum is 55.

The spelling of 21780412968601 in words is "twenty-one trillion, seven hundred eighty billion, four hundred twelve million, nine hundred sixty-eight thousand, six hundred one".