21223247077 has 4 divisors (see below), whose sum is σ = 21239713260. Its totient is φ = 21206780896.

The previous prime is 21223247051. The next prime is 21223247119. The reversal of 21223247077 is 77074232212.

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 10825570116 + 10397676961 = 104046^2 + 101969^2 .

It is a cyclic number.

It is not a de Polignac number, because 21223247077 - 2⁷ = 21223246949 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 (21223247047) 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, 8231158 + ... + 8233735.

It is an arithmetic number, because the mean of its divisors is an integer number (5309928315).

Almost surely, 2^21223247077 is an apocalyptic number.

It is an amenable number.

21223247077 is a deficient number, since it is larger than the sum of its proper divisors (16466183).

21223247077 is a wasteful number, since it uses less digits than its factorization.

21223247077 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16466182.

The product of its (nonzero) digits is 65856, while the sum is 37.

Adding to 21223247077 its reverse (77074232212), we get a palindrome (98297479289).

The spelling of 21223247077 in words is "twenty-one billion, two hundred twenty-three million, two hundred forty-seven thousand, seventy-seven".