1399699581921 has 9 divisors (see below), whose sum is σ = 2021793411729. Its totient is φ = 933130688436.

The previous prime is 1399699581911. The next prime is 1399699581941. The reversal of 1399699581921 is 1291859969931.

The square root of 1399699581921 is 1183089.

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

1399699581921 is a `hidden beast` number, since 1 + 39 + 9 + 6 + 9 + 9 + 581 + 9 + 2 + 1 = 666.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 1399699581921 - 2⁹ = 1399699581409 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1399699581921.

It is not an unprimeable number, because it can be changed into a prime (1399699581901) 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, 3352086 + ... + 3746448.

Almost surely, 2^{1399699581921} is an apocalyptic number.

1399699581921 is the 1183089-th square number.

1399699581921 is the 591545-th centered octagonal number.

It is an amenable number.

1399699581921 is a deficient number, since it is larger than the sum of its proper divisors (622093829808).

1399699581921 is an frugal number, since it uses more digits than its factorization.

1399699581921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 788732 (or 394366 counting only the distinct ones).

The product of its digits is 85030560, while the sum is 72.

The spelling of 1399699581921 in words is "one trillion, three hundred ninety-nine billion, six hundred ninety-nine million, five hundred eighty-one thousand, nine hundred twenty-one".