19997204621 has 8 divisors (see below), whose sum is σ = 20043617088. Its totient is φ = 19950840000.

The previous prime is 19997204597. The next prime is 19997204629. The reversal of 19997204621 is 12640279991.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 19997204621 - 2¹⁸ = 19996942477 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 19997204621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19997204629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 904661 + ... + 926501.

It is an arithmetic number, because the mean of its divisors is an integer number (2505452136).

Almost surely, 2^19997204621 is an apocalyptic number.

It is an amenable number.

19997204621 is a deficient number, since it is larger than the sum of its proper divisors (46412467).

19997204621 is a wasteful number, since it uses less digits than its factorization.

19997204621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23923.

The product of its (nonzero) digits is 489888, while the sum is 50.

The spelling of 19997204621 in words is "nineteen billion, nine hundred ninety-seven million, two hundred four thousand, six hundred twenty-one".