99940639 has 2 divisors, whose sum is σ = 99940640.
Its totient is φ = 99940638.
The previous prime is 99940597. The next prime is 99940693. The reversal of 99940639 is 93604999.
Together with next prime (99940693) it forms an Ormiston pair, because they use the same digits, order apart.
It is a weak prime.
It is an emirp because it is prime and its reverse (93604999) is a distict prime.
It is a cyclic number.
It is a de Polignac number, because none of the positive numbers 2k-99940639 is a prime.
It is a junction number, because it is equal to n+sod(n) for n = 99940592 and 99940601.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (99943639) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49970319 + 49970320.
It is an arithmetic number, because the mean of its divisors is an integer number (49970320).
Almost surely, 299940639 is an apocalyptic number.
99940639 is a deficient number, since it is larger than the sum of its proper divisors (1).
99940639 is an equidigital number, since it uses as much as digits as its factorization.
99940639 is an evil number, because the sum of its binary digits is even.
The product of its (nonzero) digits is 472392, while the sum is 49.
The square root of 99940639 is about 9997.0315094032.
The cubic root of 99940639 is about 464.0670220640.
The spelling of 99940639 in words is "ninety-nine million, nine hundred forty thousand, six hundred thirty-nine".