1564866421 has 4 divisors (see below), whose sum is σ = 1565337312. Its totient is φ = 1564395532.

The previous prime is 1564866403. The next prime is 1564866431. The reversal of 1564866421 is 1246684651.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1246684651 = 83 ⋅15020297.

It is a cyclic number.

It is not a de Polignac number, because 1564866421 - 2¹⁵ = 1564833653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1564866431) 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, 230425 + ... + 237118.

It is an arithmetic number, because the mean of its divisors is an integer number (391334328).

Almost surely, 2^1564866421 is an apocalyptic number.

It is an amenable number.

1564866421 is a deficient number, since it is larger than the sum of its proper divisors (470891).

1564866421 is an equidigital number, since it uses as much as digits as its factorization.

1564866421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 470890.

The product of its digits is 276480, while the sum is 43.

The square root of 1564866421 is about 39558.3925482318. The cubic root of 1564866421 is about 1160.9827237552.

The spelling of 1564866421 in words is "one billion, five hundred sixty-four million, eight hundred sixty-six thousand, four hundred twenty-one".