31994777729 has 2 divisors, whose sum is σ = 31994777730. Its totient is φ = 31994777728.

The previous prime is 31994777707. The next prime is 31994777747. The reversal of 31994777729 is 92777749913.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26486911504 + 5507866225 = 162748^2 + 74215^2 .

It is a cyclic number.

It is not a de Polignac number, because 31994777729 - 2¹² = 31994773633 is a prime.

It is a super-2 number, since 2×31994777729² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (31994776729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15997388864 + 15997388865.

It is an arithmetic number, because the mean of its divisors is an integer number (15997388865).

Almost surely, 2^31994777729 is an apocalyptic number.

It is an amenable number.

31994777729 is a deficient number, since it is larger than the sum of its proper divisors (1).

31994777729 is an equidigital number, since it uses as much as digits as its factorization.

31994777729 is an evil number, because the sum of its binary digits is even.

The product of its digits is 42007896, while the sum is 65.

The spelling of 31994777729 in words is "thirty-one billion, nine hundred ninety-four million, seven hundred seventy-seven thousand, seven hundred twenty-nine".