1820091521 has 2 divisors, whose sum is σ = 1820091522. Its totient is φ = 1820091520.

The previous prime is 1820091509. The next prime is 1820091541. The reversal of 1820091521 is 1251900281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 947716225 + 872375296 = 30785^2 + 29536^2 .

It is a cyclic number.

It is not a de Polignac number, because 1820091521 - 2¹⁴ = 1820075137 is a prime.

It is not a weakly prime, because it can be changed into another prime (1820091541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 910045760 + 910045761.

It is an arithmetic number, because the mean of its divisors is an integer number (910045761).

Almost surely, 2^1820091521 is an apocalyptic number.

It is an amenable number.

1820091521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1820091521 is an equidigital number, since it uses as much as digits as its factorization.

1820091521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 29.

The square root of 1820091521 is about 42662.5306445832. The cubic root of 1820091521 is about 1220.9496147255.

The spelling of 1820091521 in words is "one billion, eight hundred twenty million, ninety-one thousand, five hundred twenty-one".