1564360721 has 18 divisors (see below), whose sum is σ = 2000246850. Its totient is φ = 1218977760.

The previous prime is 1564360711. The next prime is 1564360729. The reversal of 1564360721 is 1270634651.

It can be written as a sum of positive squares in only one way, i.e., 1163560321 + 400800400 = 34111^2 + 20020^2 .

It is not a de Polignac number, because 1564360721 - 2¹⁸ = 1564098577 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1564360729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 125996 + ... + 137853.

It is an arithmetic number, because the mean of its divisors is an integer number (111124825).

Almost surely, 2^1564360721 is an apocalyptic number.

1564360721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1564360721 is a deficient number, since it is larger than the sum of its proper divisors (435886129).

1564360721 is a wasteful number, since it uses less digits than its factorization.

1564360721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263885 (or 263867 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 35.

The square root of 1564360721 is about 39552.0002149070. Note that the first 3 decimals coincide. The cubic root of 1564360721 is about 1160.8576497744.

The spelling of 1564360721 in words is "one billion, five hundred sixty-four million, three hundred sixty thousand, seven hundred twenty-one".