21311320747 has 2 divisors, whose sum is σ = 21311320748. Its totient is φ = 21311320746.

The previous prime is 21311320727. The next prime is 21311320753. The reversal of 21311320747 is 74702311312.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21311320747 is a prime.

It is not a weakly prime, because it can be changed into another prime (21311320727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655660373 + 10655660374.

It is an arithmetic number, because the mean of its divisors is an integer number (10655660374).

Almost surely, 2^21311320747 is an apocalyptic number.

21311320747 is a deficient number, since it is larger than the sum of its proper divisors (1).

21311320747 is an equidigital number, since it uses as much as digits as its factorization.

21311320747 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7056, while the sum is 31.

The spelling of 21311320747 in words is "twenty-one billion, three hundred eleven million, three hundred twenty thousand, seven hundred forty-seven".