15630721 has 4 divisors (see below), whose sum is σ = 15850944. Its totient is φ = 15410500.

The previous prime is 15630697. The next prime is 15630737. The reversal of 15630721 is 12703651.

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 15630721 - 2²³ = 7242113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15630751) 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, 110005 + ... + 110146.

It is an arithmetic number, because the mean of its divisors is an integer number (3962736).

Almost surely, 2^15630721 is an apocalyptic number.

It is an amenable number.

15630721 is a deficient number, since it is larger than the sum of its proper divisors (220223).

15630721 is an equidigital number, since it uses as much as digits as its factorization.

15630721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220222.

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 15630721 is about 3953.5706646018. The cubic root of 15630721 is about 250.0305082768.

The spelling of 15630721 in words is "fifteen million, six hundred thirty thousand, seven hundred twenty-one".