1631620968721 has 4 divisors (see below), whose sum is σ = 1646060092452. Its totient is φ = 1617181844992.

The previous prime is 1631620968631. The next prime is 1631620968727. The reversal of 1631620968721 is 1278690261361.

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 67983261696 + 1563637707025 = 260736^2 + 1250455^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1631620968721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1631620968727) 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, 7219561696 + ... + 7219561921.

It is an arithmetic number, because the mean of its divisors is an integer number (411515023113).

Almost surely, 2^{1631620968721} is an apocalyptic number.

It is an amenable number.

1631620968721 is a deficient number, since it is larger than the sum of its proper divisors (14439123731).

1631620968721 is a wasteful number, since it uses less digits than its factorization.

1631620968721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14439123730.

The product of its (nonzero) digits is 1306368, while the sum is 52.

The spelling of 1631620968721 in words is "one trillion, six hundred thirty-one billion, six hundred twenty million, nine hundred sixty-eight thousand, seven hundred twenty-one".