79669781 has 2 divisors, whose sum is σ = 79669782. Its totient is φ = 79669780.

The previous prime is 79669763. The next prime is 79669813. The reversal of 79669781 is 18796697.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69872881 + 9796900 = 8359^2 + 3130^2 .

It is a cyclic number.

It is not a de Polignac number, because 79669781 - 2¹⁴ = 79653397 is a prime.

It is a super-2 number, since 2×79669781² = 12694548009175922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (79669741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39834890 + 39834891.

It is an arithmetic number, because the mean of its divisors is an integer number (39834891).

Almost surely, 2^79669781 is an apocalyptic number.

It is an amenable number.

79669781 is a deficient number, since it is larger than the sum of its proper divisors (1).

79669781 is an equidigital number, since it uses as much as digits as its factorization.

79669781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1143072, while the sum is 53.

The square root of 79669781 is about 8925.7930179901. The cubic root of 79669781 is about 430.2932576793.

The spelling of 79669781 in words is "seventy-nine million, six hundred sixty-nine thousand, seven hundred eighty-one".