1373517721 has 3 divisors (see below), whose sum is σ = 1373554783. Its totient is φ = 1373480660.

The previous prime is 1373517709. The next prime is 1373517727. The reversal of 1373517721 is 1277153731.

The square root of 1373517721 is 37061.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 1234749321 + 138768400 = 35139^2 + 11780^2 .

It is not a de Polignac number, because 1373517721 - 2⁵ = 1373517689 is a prime.

It is a super-4 number, since 4×1373517721⁴ (a number of 38 digits) contains 4444 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1373517727) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 18531 + ... + 55591.

Almost surely, 2^1373517721 is an apocalyptic number.

1373517721 is the 37061-st square number.

1373517721 is the 18531-st centered octagonal number.

It is an amenable number.

1373517721 is a deficient number, since it is larger than the sum of its proper divisors (37062).

1373517721 is an frugal number, since it uses more digits than its factorization.

1373517721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74122 (or 37061 counting only the distinct ones).

The product of its digits is 30870, while the sum is 37.

The cubic root of 1373517721 is about 1111.5903187051.

The spelling of 1373517721 in words is "one billion, three hundred seventy-three million, five hundred seventeen thousand, seven hundred twenty-one".