1821861749 has 2 divisors, whose sum is σ = 1821861750. Its totient is φ = 1821861748.

The previous prime is 1821861737. The next prime is 1821861781. The reversal of 1821861749 is 9471681281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1074659524 + 747202225 = 32782^2 + 27335^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1821861749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1821861709) 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, 910930874 + 910930875.

It is an arithmetic number, because the mean of its divisors is an integer number (910930875).

Almost surely, 2^1821861749 is an apocalyptic number.

It is an amenable number.

1821861749 is a deficient number, since it is larger than the sum of its proper divisors (1).

1821861749 is an equidigital number, since it uses as much as digits as its factorization.

1821861749 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 193536, while the sum is 47.

The square root of 1821861749 is about 42683.2724729489. The cubic root of 1821861749 is about 1221.3453198925.

The spelling of 1821861749 in words is "one billion, eight hundred twenty-one million, eight hundred sixty-one thousand, seven hundred forty-nine".