1521739991 has 2 divisors, whose sum is σ = 1521739992. Its totient is φ = 1521739990.

The previous prime is 1521739981. The next prime is 1521739993. The reversal of 1521739991 is 1999371251.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1521739991 is a prime.

Together with 1521739993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1521739993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 760869995 + 760869996.

It is an arithmetic number, because the mean of its divisors is an integer number (760869996).

Almost surely, 2^1521739991 is an apocalyptic number.

1521739991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1521739991 is an equidigital number, since it uses as much as digits as its factorization.

1521739991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 153090, while the sum is 47.

The square root of 1521739991 is about 39009.4859104808. The cubic root of 1521739991 is about 1150.2179778362.

The spelling of 1521739991 in words is "one billion, five hundred twenty-one million, seven hundred thirty-nine thousand, nine hundred ninety-one".