996907721 has 2 divisors, whose sum is σ = 996907722. Its totient is φ = 996907720.

The previous prime is 996907697. The next prime is 996907729. The reversal of 996907721 is 127709699.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 891619600 + 105288121 = 29860^2 + 10261^2 .

It is a cyclic number.

It is not a de Polignac number, because 996907721 - 2²² = 992713417 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 996907721.

It is not a weakly prime, because it can be changed into another prime (996907729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 498453860 + 498453861.

It is an arithmetic number, because the mean of its divisors is an integer number (498453861).

Almost surely, 2^996907721 is an apocalyptic number.

It is an amenable number.

996907721 is a deficient number, since it is larger than the sum of its proper divisors (1).

996907721 is an equidigital number, since it uses as much as digits as its factorization.

996907721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 428652, while the sum is 50.

The square root of 996907721 is about 31573.8455212538. The cubic root of 996907721 is about 998.9681760388.

The spelling of 996907721 in words is "nine hundred ninety-six million, nine hundred seven thousand, seven hundred twenty-one".