21223201657 has 4 divisors (see below), whose sum is σ = 24255087616. Its totient is φ = 18191315700.

The previous prime is 21223201589. The next prime is 21223201687. The reversal of 21223201657 is 75610232212.

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 21223201657 - 2¹¹ = 21223199609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21223201687) 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, 1515942969 + ... + 1515942982.

It is an arithmetic number, because the mean of its divisors is an integer number (6063771904).

Almost surely, 2^21223201657 is an apocalyptic number.

It is an amenable number.

21223201657 is a deficient number, since it is larger than the sum of its proper divisors (3031885959).

21223201657 is an equidigital number, since it uses as much as digits as its factorization.

21223201657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3031885958.

The product of its (nonzero) digits is 10080, while the sum is 31.

Adding to 21223201657 its reverse (75610232212), we get a palindrome (96833433869).

The spelling of 21223201657 in words is "twenty-one billion, two hundred twenty-three million, two hundred one thousand, six hundred fifty-seven".