1820375561 has 2 divisors, whose sum is σ = 1820375562. Its totient is φ = 1820375560.

The previous prime is 1820375551. The next prime is 1820375567. The reversal of 1820375561 is 1655730281.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1357480336 + 462895225 = 36844^2 + 21515^2 .

It is a cyclic number.

It is not a de Polignac number, because 1820375561 - 2⁶ = 1820375497 is a prime.

It is a super-3 number, since 3×1820375561³ (a number of 29 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (1820375567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 910187780 + 910187781.

It is an arithmetic number, because the mean of its divisors is an integer number (910187781).

Almost surely, 2^1820375561 is an apocalyptic number.

It is an amenable number.

1820375561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1820375561 is an equidigital number, since it uses as much as digits as its factorization.

1820375561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 50400, while the sum is 38.

The square root of 1820375561 is about 42665.8594311658. The cubic root of 1820375561 is about 1221.0131244421.

The spelling of 1820375561 in words is "one billion, eight hundred twenty million, three hundred seventy-five thousand, five hundred sixty-one".