1931921 has 2 divisors, whose sum is σ = 1931922. Its totient is φ = 1931920.

The previous prime is 1931887. The next prime is 1931927. The reversal of 1931921 is 1291391.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1661521 + 270400 = 1289^2 + 520^2 .

It is an emirp because it is prime and its reverse (1291391) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1931921 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1931927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 965960 + 965961.

It is an arithmetic number, because the mean of its divisors is an integer number (965961).

2^1931921 is an apocalyptic number.

It is an amenable number.

1931921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1931921 is an equidigital number, since it uses as much as digits as its factorization.

1931921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 486, while the sum is 26.

The square root of 1931921 is about 1389.9356100194. The cubic root of 1931921 is about 124.5460010761.

The spelling of 1931921 in words is "one million, nine hundred thirty-one thousand, nine hundred twenty-one".