1321620157621 has 4 divisors (see below), whose sum is σ = 1399362519852. Its totient is φ = 1243877795392.

The previous prime is 1321620157619. The next prime is 1321620157643. The reversal of 1321620157621 is 1267510261231.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1018916623396 + 302703534225 = 1009414^2 + 550185^2 .

It is a cyclic number.

It is not a de Polignac number, because 1321620157621 - 2¹ = 1321620157619 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1321620157661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38871181090 + ... + 38871181123.

It is an arithmetic number, because the mean of its divisors is an integer number (349840629963).

Almost surely, 2^{1321620157621} is an apocalyptic number.

It is an amenable number.

1321620157621 is a deficient number, since it is larger than the sum of its proper divisors (77742362231).

1321620157621 is an equidigital number, since it uses as much as digits as its factorization.

1321620157621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77742362230.

The product of its (nonzero) digits is 30240, while the sum is 37.

The spelling of 1321620157621 in words is "one trillion, three hundred twenty-one billion, six hundred twenty million, one hundred fifty-seven thousand, six hundred twenty-one".