1321670521 has 4 divisors (see below), whose sum is σ = 1324681600. Its totient is φ = 1318659444.

The previous prime is 1321670479. The next prime is 1321670543. The reversal of 1321670521 is 1250761231.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1321670521 - 2⁷ = 1321670393 is a prime.

It is a super-2 number, since 2×1321670521² = 3493625932160822882, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1321670521.

It is not an unprimeable number, because it can be changed into a prime (1321677521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1504881 + ... + 1505758.

It is an arithmetic number, because the mean of its divisors is an integer number (331170400).

Almost surely, 2^1321670521 is an apocalyptic number.

It is an amenable number.

1321670521 is a deficient number, since it is larger than the sum of its proper divisors (3011079).

1321670521 is an equidigital number, since it uses as much as digits as its factorization.

1321670521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3011078.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 1321670521 is about 36354.7867687324. The cubic root of 1321670521 is about 1097.4238671562.

The spelling of 1321670521 in words is "one billion, three hundred twenty-one million, six hundred seventy thousand, five hundred twenty-one".