19973021 has 4 divisors (see below), whose sum is σ = 20617344. Its totient is φ = 19328700.

The previous prime is 19972987. The next prime is 19973029. The reversal of 19973021 is 12037991.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 19973021 - 2⁶ = 19972957 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19973029) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 322115 + ... + 322176.

It is an arithmetic number, because the mean of its divisors is an integer number (5154336).

Almost surely, 2^19973021 is an apocalyptic number.

It is an amenable number.

19973021 is a deficient number, since it is larger than the sum of its proper divisors (644323).

19973021 is an equidigital number, since it uses as much as digits as its factorization.

19973021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 644322.

The product of its (nonzero) digits is 3402, while the sum is 32.

The square root of 19973021 is about 4469.1185931904. The cubic root of 19973021 is about 271.3196529487.

The spelling of 19973021 in words is "nineteen million, nine hundred seventy-three thousand, twenty-one".