264400021 has 4 divisors (see below), whose sum is σ = 270848844. Its totient is φ = 257951200.

The previous prime is 264400013. The next prime is 264400033. The reversal of 264400021 is 120004462.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5640625 + 258759396 = 2375^2 + 16086^2 .

It is a cyclic number.

It is not a de Polignac number, because 264400021 - 2³ = 264400013 is a prime.

It is a super-2 number, since 2×264400021² = 139814742209600882, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (264400061) 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, 3224350 + ... + 3224431.

It is an arithmetic number, because the mean of its divisors is an integer number (67712211).

Almost surely, 2^264400021 is an apocalyptic number.

It is an amenable number.

264400021 is a deficient number, since it is larger than the sum of its proper divisors (6448823).

264400021 is an equidigital number, since it uses as much as digits as its factorization.

264400021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6448822.

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 264400021 is about 16260.3819450836. The cubic root of 264400021 is about 641.8307128629.

Adding to 264400021 its reverse (120004462), we get a palindrome (384404483).

The spelling of 264400021 in words is "two hundred sixty-four million, four hundred thousand, twenty-one".