21021020197 has 8 divisors (see below), whose sum is σ = 21893231232. Its totient is φ = 20164813200.

The previous prime is 21021020161. The next prime is 21021020239. The reversal of 21021020197 is 79102012012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21021020197 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021020117) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3998329 + ... + 4003582.

It is an arithmetic number, because the mean of its divisors is an integer number (2736653904).

Almost surely, 2^21021020197 is an apocalyptic number.

It is an amenable number.

21021020197 is a deficient number, since it is larger than the sum of its proper divisors (872211035).

21021020197 is an equidigital number, since it uses as much as digits as its factorization.

21021020197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8002019.

The product of its (nonzero) digits is 504, while the sum is 25.

The spelling of 21021020197 in words is "twenty-one billion, twenty-one million, twenty thousand, one hundred ninety-seven".