1379208721 has 16 divisors (see below), whose sum is σ = 1535526720. Its totient is φ = 1228198720.

The previous prime is 1379208683. The next prime is 1379208737. The reversal of 1379208721 is 1278029731.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 1379208721 - 2²¹ = 1377111569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1379208791) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 186531 + ... + 193783.

It is an arithmetic number, because the mean of its divisors is an integer number (95970420).

Almost surely, 2^1379208721 is an apocalyptic number.

1379208721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1379208721 is a deficient number, since it is larger than the sum of its proper divisors (156317999).

1379208721 is a wasteful number, since it uses less digits than its factorization.

1379208721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7616.

The product of its (nonzero) digits is 42336, while the sum is 40.

The square root of 1379208721 is about 37137.6994575593. The cubic root of 1379208721 is about 1113.1234486584.

It can be divided in two parts, 137920 and 8721, that added together give a palindrome (146641).

The spelling of 1379208721 in words is "one billion, three hundred seventy-nine million, two hundred eight thousand, seven hundred twenty-one".