139688491 has 2 divisors, whose sum is σ = 139688492. Its totient is φ = 139688490.

The previous prime is 139688401. The next prime is 139688509. The reversal of 139688491 is 194886931.

139688491 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-139688491 is a prime.

It is not a weakly prime, because it can be changed into another prime (139688401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69844245 + 69844246.

It is an arithmetic number, because the mean of its divisors is an integer number (69844246).

Almost surely, 2^139688491 is an apocalyptic number.

139688491 is a deficient number, since it is larger than the sum of its proper divisors (1).

139688491 is an equidigital number, since it uses as much as digits as its factorization.

139688491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 373248, while the sum is 49.

The square root of 139688491 is about 11818.9885777083. The cubic root of 139688491 is about 518.8640030858.

The spelling of 139688491 in words is "one hundred thirty-nine million, six hundred eighty-eight thousand, four hundred ninety-one".