20971954397 has 4 divisors (see below), whose sum is σ = 20974857120. Its totient is φ = 20969051676.

The previous prime is 20971954379. The next prime is 20971954417. The reversal of 20971954397 is 79345917902.

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 20971954397 - 2³² = 16676987101 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 (20971924397) 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, 1440497 + ... + 1454982.

It is an arithmetic number, because the mean of its divisors is an integer number (5243714280).

Almost surely, 2^20971954397 is an apocalyptic number.

It is an amenable number.

20971954397 is a deficient number, since it is larger than the sum of its proper divisors (2902723).

20971954397 is an equidigital number, since it uses as much as digits as its factorization.

20971954397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2902722.

The product of its (nonzero) digits is 4286520, while the sum is 56.

The spelling of 20971954397 in words is "twenty billion, nine hundred seventy-one million, nine hundred fifty-four thousand, three hundred ninety-seven".