21361720897 has 8 divisors (see below), whose sum is σ = 23313287232. Its totient is φ = 19411753200.

The previous prime is 21361720883. The next prime is 21361720907. The reversal of 21361720897 is 79802716312.

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-21361720897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21361720297) 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, 371629 + ... + 425242.

It is an arithmetic number, because the mean of its divisors is an integer number (2914160904).

Almost surely, 2^21361720897 is an apocalyptic number.

It is an amenable number.

21361720897 is a deficient number, since it is larger than the sum of its proper divisors (1951566335).

21361720897 is a wasteful number, since it uses less digits than its factorization.

21361720897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 799319.

The product of its (nonzero) digits is 254016, while the sum is 46.

The spelling of 21361720897 in words is "twenty-one billion, three hundred sixty-one million, seven hundred twenty thousand, eight hundred ninety-seven".