63831721 has 2 divisors, whose sum is σ = 63831722. Its totient is φ = 63831720.

The previous prime is 63831709. The next prime is 63831767. The reversal of 63831721 is 12713836.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 63680400 + 151321 = 7980^2 + 389^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-63831721 is a prime.

It is not a weakly prime, because it can be changed into another prime (63831701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 31915860 + 31915861.

It is an arithmetic number, because the mean of its divisors is an integer number (31915861).

Almost surely, 2^63831721 is an apocalyptic number.

It is an amenable number.

63831721 is a deficient number, since it is larger than the sum of its proper divisors (1).

63831721 is an equidigital number, since it uses as much as digits as its factorization.

63831721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6048, while the sum is 31.

The square root of 63831721 is about 7989.4756398652. The cubic root of 63831721 is about 399.6491110323.

The spelling of 63831721 in words is "sixty-three million, eight hundred thirty-one thousand, seven hundred twenty-one".