63994721 has 4 divisors (see below), whose sum is σ = 73136832. Its totient is φ = 54852612.

The previous prime is 63994703. The next prime is 63994729. The reversal of 63994721 is 12749936.

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 63994721 - 2⁶ = 63994657 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (63994729) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4571045 + ... + 4571058.

It is an arithmetic number, because the mean of its divisors is an integer number (18284208).

Almost surely, 2^63994721 is an apocalyptic number.

It is an amenable number.

63994721 is a deficient number, since it is larger than the sum of its proper divisors (9142111).

63994721 is an equidigital number, since it uses as much as digits as its factorization.

63994721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9142110.

The product of its digits is 81648, while the sum is 41.

The square root of 63994721 is about 7999.6700556960. The cubic root of 63994721 is about 399.9890017809.

The spelling of 63994721 in words is "sixty-three million, nine hundred ninety-four thousand, seven hundred twenty-one".