21231372077 has 4 divisors (see below), whose sum is σ = 21725124960. Its totient is φ = 20737619196.

The previous prime is 21231372031. The next prime is 21231372119. The reversal of 21231372077 is 77027313212.

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 21231372077 - 2¹² = 21231367981 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 (21231372277) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 246876377 + ... + 246876462.

It is an arithmetic number, because the mean of its divisors is an integer number (5431281240).

Almost surely, 2^21231372077 is an apocalyptic number.

It is an amenable number.

21231372077 is a deficient number, since it is larger than the sum of its proper divisors (493752883).

21231372077 is an equidigital number, since it uses as much as digits as its factorization.

21231372077 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 493752882.

The product of its (nonzero) digits is 24696, while the sum is 35.

Adding to 21231372077 its reverse (77027313212), we get a palindrome (98258685289).

The spelling of 21231372077 in words is "twenty-one billion, two hundred thirty-one million, three hundred seventy-two thousand, seventy-seven".