42663721 has 4 divisors (see below), whose sum is σ = 44909200. Its totient is φ = 40418244.

The previous prime is 42663679. The next prime is 42663737. The reversal of 42663721 is 12736624.

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 not a de Polignac number, because 42663721 - 2¹⁵ = 42630953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42663221) 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, 1122711 + ... + 1122748.

It is an arithmetic number, because the mean of its divisors is an integer number (11227300).

Almost surely, 2^42663721 is an apocalyptic number.

It is an amenable number.

42663721 is a deficient number, since it is larger than the sum of its proper divisors (2245479).

42663721 is a wasteful number, since it uses less digits than its factorization.

42663721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2245478.

The product of its digits is 12096, while the sum is 31.

The square root of 42663721 is about 6531.7471628960. The cubic root of 42663721 is about 349.4241442193.

The spelling of 42663721 in words is "forty-two million, six hundred sixty-three thousand, seven hundred twenty-one".