997720051 has 2 divisors, whose sum is σ = 997720052. Its totient is φ = 997720050.

The previous prime is 997720049. The next prime is 997720081. The reversal of 997720051 is 150027799.

It is a weak prime.

It is an emirp because it is prime and its reverse (150027799) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 997720051 - 2¹ = 997720049 is a prime.

Together with 997720049, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 997719986 and 997720013.

It is not a weakly prime, because it can be changed into another prime (997720081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 498860025 + 498860026.

It is an arithmetic number, because the mean of its divisors is an integer number (498860026).

Almost surely, 2^997720051 is an apocalyptic number.

997720051 is a deficient number, since it is larger than the sum of its proper divisors (1).

997720051 is an equidigital number, since it uses as much as digits as its factorization.

997720051 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 39690, while the sum is 40.

The square root of 997720051 is about 31586.7068717206. The cubic root of 997720051 is about 999.2394386931.

The spelling of 997720051 in words is "nine hundred ninety-seven million, seven hundred twenty thousand, fifty-one".