921942991 has 2 divisors, whose sum is σ = 921942992. Its totient is φ = 921942990.

The previous prime is 921942961. The next prime is 921943067. The reversal of 921942991 is 199249129.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-921942991 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (921942941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 460971495 + 460971496.

It is an arithmetic number, because the mean of its divisors is an integer number (460971496).

Almost surely, 2^921942991 is an apocalyptic number.

921942991 is a deficient number, since it is larger than the sum of its proper divisors (1).

921942991 is an equidigital number, since it uses as much as digits as its factorization.

921942991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 104976, while the sum is 46.

The square root of 921942991 is about 30363.5141411530. The cubic root of 921942991 is about 973.2730300440.

The spelling of 921942991 in words is "nine hundred twenty-one million, nine hundred forty-two thousand, nine hundred ninety-one".