990718193921 has 2 divisors, whose sum is σ = 990718193922. Its totient is φ = 990718193920.

The previous prime is 990718193917. The next prime is 990718193951. The reversal of 990718193921 is 129391817099.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 929226593296 + 61491600625 = 963964^2 + 247975^2 .

It is a cyclic number.

It is not a de Polignac number, because 990718193921 - 2² = 990718193917 is a prime.

It is a super-2 number, since 2×990718193921² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (990718193951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495359096960 + 495359096961.

It is an arithmetic number, because the mean of its divisors is an integer number (495359096961).

Almost surely, 2^990718193921 is an apocalyptic number.

It is an amenable number.

990718193921 is a deficient number, since it is larger than the sum of its proper divisors (1).

990718193921 is an equidigital number, since it uses as much as digits as its factorization.

990718193921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2204496, while the sum is 59.

The spelling of 990718193921 in words is "nine hundred ninety billion, seven hundred eighteen million, one hundred ninety-three thousand, nine hundred twenty-one".