20997570097949 has 4 divisors (see below), whose sum is σ = 21001875530364. Its totient is φ = 20993264665536.

The previous prime is 20997570097913. The next prime is 20997570097951. The reversal of 20997570097949 is 94979007579902.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12460596421849 + 8536973676100 = 3529957^2 + 2921810^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20997570097949 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 20997570097949.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20997570097549) 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, 2152708892 + ... + 2152718645.

It is an arithmetic number, because the mean of its divisors is an integer number (5250468882591).

Almost surely, 2^{20997570097949} is an apocalyptic number.

It is an amenable number.

20997570097949 is a deficient number, since it is larger than the sum of its proper divisors (4305432415).

20997570097949 is an equidigital number, since it uses as much as digits as its factorization.

20997570097949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4305432414.

The product of its (nonzero) digits is 810152280, while the sum is 77.

The spelling of 20997570097949 in words is "twenty trillion, nine hundred ninety-seven billion, five hundred seventy million, ninety-seven thousand, nine hundred forty-nine".