999621397 has 2 divisors, whose sum is σ = 999621398. Its totient is φ = 999621396.

The previous prime is 999621379. The next prime is 999621401. The reversal of 999621397 is 793126999.

Together with previous prime (999621379) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 751527396 + 248094001 = 27414^2 + 15751^2 .

It is a cyclic number.

It is not a de Polignac number, because 999621397 - 2⁷ = 999621269 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999627397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499810698 + 499810699.

It is an arithmetic number, because the mean of its divisors is an integer number (499810699).

Almost surely, 2^999621397 is an apocalyptic number.

It is an amenable number.

999621397 is a deficient number, since it is larger than the sum of its proper divisors (1).

999621397 is an equidigital number, since it uses as much as digits as its factorization.

999621397 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1653372, while the sum is 55.

The square root of 999621397 is about 31616.7897959296. The cubic root of 999621397 is about 999.8737830700.

The spelling of 999621397 in words is "nine hundred ninety-nine million, six hundred twenty-one thousand, three hundred ninety-seven".