1942781921 has 2 divisors, whose sum is σ = 1942781922. Its totient is φ = 1942781920.

The previous prime is 1942781851. The next prime is 1942781933. The reversal of 1942781921 is 1291872491.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1557091600 + 385690321 = 39460^2 + 19639^2 .

It is a cyclic number.

It is not a de Polignac number, because 1942781921 - 2¹⁴ = 1942765537 is a prime.

It is not a weakly prime, because it can be changed into another prime (1942781941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 971390960 + 971390961.

It is an arithmetic number, because the mean of its divisors is an integer number (971390961).

Almost surely, 2^1942781921 is an apocalyptic number.

It is an amenable number.

1942781921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1942781921 is an equidigital number, since it uses as much as digits as its factorization.

1942781921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72576, while the sum is 44.

The square root of 1942781921 is about 44076.9999092497. Note that the first 4 decimals coincide. The cubic root of 1942781921 is about 1247.7895699833.

The spelling of 1942781921 in words is "one billion, nine hundred forty-two million, seven hundred eighty-one thousand, nine hundred twenty-one".