1399936209721 has 27 divisors (see below), whose sum is σ = 1702611574671. Its totient is φ = 1147617605904.

The previous prime is 1399936209703. The next prime is 1399936209731. The reversal of 1399936209721 is 1279026399931.

The square root of 1399936209721 is 1183189.

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

It can be written as a sum of positive squares in only one way, i.e., 964204199721 + 435732010000 = 981939^2 + 660100^2 .

It is not a de Polignac number, because 1399936209721 - 2¹³ = 1399936201529 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1399936209721.

It is not an unprimeable number, because it can be changed into a prime (1399936209731) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 190489755 + ... + 190497103.

Almost surely, 2^{1399936209721} is an apocalyptic number.

1399936209721 is the 1183189-th square number.

1399936209721 is the 591595-th centered octagonal number.

It is an amenable number.

1399936209721 is a deficient number, since it is larger than the sum of its proper divisors (302675364950).

1399936209721 is an frugal number, since it uses more digits than its factorization.

1399936209721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14758 (or 7379 counting only the distinct ones).

The product of its (nonzero) digits is 9920232, while the sum is 61.

The spelling of 1399936209721 in words is "one trillion, three hundred ninety-nine billion, nine hundred thirty-six million, two hundred nine thousand, seven hundred twenty-one".