102691991 has 2 divisors, whose sum is σ = 102691992. Its totient is φ = 102691990.

The previous prime is 102691943. The next prime is 102692047. The reversal of 102691991 is 199196201.

It is a weak prime.

It is an emirp because it is prime and its reverse (199196201) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 102691991 - 2¹⁴ = 102675607 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (102691091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 51345995 + 51345996.

It is an arithmetic number, because the mean of its divisors is an integer number (51345996).

Almost surely, 2^102691991 is an apocalyptic number.

102691991 is a deficient number, since it is larger than the sum of its proper divisors (1).

102691991 is an equidigital number, since it uses as much as digits as its factorization.

102691991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8748, while the sum is 38.

The square root of 102691991 is about 10133.7056894307. The cubic root of 102691991 is about 468.2870967752.

The spelling of 102691991 in words is "one hundred two million, six hundred ninety-one thousand, nine hundred ninety-one".