64243721 has 2 divisors, whose sum is σ = 64243722. Its totient is φ = 64243720.

The previous prime is 64243709. The next prime is 64243727. The reversal of 64243721 is 12734246.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64176121 + 67600 = 8011^2 + 260^2 .

It is a cyclic number.

It is not a de Polignac number, because 64243721 - 2⁶ = 64243657 is a prime.

It is not a weakly prime, because it can be changed into another prime (64243727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32121860 + 32121861.

It is an arithmetic number, because the mean of its divisors is an integer number (32121861).

Almost surely, 2^64243721 is an apocalyptic number.

It is an amenable number.

64243721 is a deficient number, since it is larger than the sum of its proper divisors (1).

64243721 is an equidigital number, since it uses as much as digits as its factorization.

64243721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8064, while the sum is 29.

The square root of 64243721 is about 8015.2180881121. The cubic root of 64243721 is about 400.5071089130.

Adding to 64243721 its reverse (12734246), we get a palindrome (76977967).

The spelling of 64243721 in words is "sixty-four million, two hundred forty-three thousand, seven hundred twenty-one".