1520721091 has 2 divisors, whose sum is σ = 1520721092. Its totient is φ = 1520721090.

The previous prime is 1520721029. The next prime is 1520721113. The reversal of 1520721091 is 1901270251.

It is a strong prime.

It is an emirp because it is prime and its reverse (1901270251) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1520721091 - 2¹⁹ = 1520196803 is a prime.

It is a super-2 number, since 2×1520721091² = 4625185273224460562, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1520721001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 760360545 + 760360546.

It is an arithmetic number, because the mean of its divisors is an integer number (760360546).

Almost surely, 2^1520721091 is an apocalyptic number.

1520721091 is a deficient number, since it is larger than the sum of its proper divisors (1).

1520721091 is an equidigital number, since it uses as much as digits as its factorization.

1520721091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1260, while the sum is 28.

The square root of 1520721091 is about 38996.4240796512. The cubic root of 1520721091 is about 1149.9612062528.

The spelling of 1520721091 in words is "one billion, five hundred twenty million, seven hundred twenty-one thousand, ninety-one".