19979797 has 2 divisors, whose sum is σ = 19979798. Its totient is φ = 19979796.

The previous prime is 19979783. The next prime is 19979803. The reversal of 19979797 is 79797991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11015761 + 8964036 = 3319^2 + 2994^2 .

It is a cyclic number.

It is not a de Polignac number, because 19979797 - 2¹⁵ = 19947029 is a prime.

It is a super-2 number, since 2×19979797² = 798384576322418, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19979737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9989898 + 9989899.

It is an arithmetic number, because the mean of its divisors is an integer number (9989899).

Almost surely, 2^19979797 is an apocalyptic number.

It is an amenable number.

19979797 is a deficient number, since it is larger than the sum of its proper divisors (1).

19979797 is an equidigital number, since it uses as much as digits as its factorization.

19979797 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2250423, while the sum is 58.

The square root of 19979797 is about 4469.8766202212. The cubic root of 19979797 is about 271.3503319015.

The spelling of 19979797 in words is "nineteen million, nine hundred seventy-nine thousand, seven hundred ninety-seven".