19797021 has 16 divisors (see below), whose sum is σ = 29635200. Its totient is φ = 13060224.

The previous prime is 19797017. The next prime is 19797023. The reversal of 19797021 is 12079791.

19797021 = 218² + 219² + ... + 411².

It is not a de Polignac number, because 19797021 - 2² = 19797017 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19797023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1161 + ... + 6398.

It is an arithmetic number, because the mean of its divisors is an integer number (1852200).

Almost surely, 2^19797021 is an apocalyptic number.

It is an amenable number.

19797021 is a deficient number, since it is larger than the sum of its proper divisors (9838179).

19797021 is an equidigital number, since it uses as much as digits as its factorization.

19797021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7665 (or 7659 counting only the distinct ones).

The product of its (nonzero) digits is 7938, while the sum is 36.

The square root of 19797021 is about 4449.3843394339. The cubic root of 19797021 is about 270.5203545329.

The spelling of 19797021 in words is "nineteen million, seven hundred ninety-seven thousand, twenty-one".