1621340431261 has 4 divisors (see below), whose sum is σ = 1621520329372. Its totient is φ = 1621160533152.

The previous prime is 1621340431253. The next prime is 1621340431283.

1621340431261 is nontrivially palindromic in base 10.

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 1021350763161 + 599989668100 = 1010619^2 + 774590^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621340431261 - 2³ = 1621340431253 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 (1621340431201) 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, 89935536 + ... + 89953561.

It is an arithmetic number, because the mean of its divisors is an integer number (405380082343).

Almost surely, 2^{1621340431261} is an apocalyptic number.

It is an amenable number.

1621340431261 is a deficient number, since it is larger than the sum of its proper divisors (179898111).

1621340431261 is an equidigital number, since it uses as much as digits as its factorization.

1621340431261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179898110.

The product of its (nonzero) digits is 20736, while the sum is 34.

The spelling of 1621340431261 in words is "one trillion, six hundred twenty-one billion, three hundred forty million, four hundred thirty-one thousand, two hundred sixty-one".