19765266921 has 63 divisors (see below), whose sum is σ = 30615816423. Its totient is φ = 12754234080.

The previous prime is 19765266919. The next prime is 19765266931. The reversal of 19765266921 is 12966256791.

The square root of 19765266921 is 140589.

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

19765266921 is a `hidden beast` number, since 1 + 97 + 6 + 526 + 6 + 9 + 21 = 666.

It can be written as a sum of positive squares in only one way, i.e., 952401321 + 18812865600 = 30861^2 + 137160^2 .

It is not a de Polignac number, because 19765266921 - 2¹ = 19765266919 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (19765266931) by changing a digit.

It is a polite number, since it can be written in 62 ways as a sum of consecutive naturals, for example, 155631960 + ... + 155632086.

Almost surely, 2^19765266921 is an apocalyptic number.

19765266921 is the 140589-th square number.

19765266921 is the 70295-th centered octagonal number.

It is an amenable number.

19765266921 is a deficient number, since it is larger than the sum of its proper divisors (10850549502).

19765266921 is an frugal number, since it uses more digits than its factorization.

19765266921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 354 (or 171 counting only the distinct ones).

The product of its digits is 2449440, while the sum is 54.

The spelling of 19765266921 in words is "nineteen billion, seven hundred sixty-five million, two hundred sixty-six thousand, nine hundred twenty-one".