725000021 has 4 divisors (see below), whose sum is σ = 726223212. Its totient is φ = 723776832.

The previous prime is 724999973. The next prime is 725000033. The reversal of 725000021 is 120000527.

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 305200900 + 419799121 = 17470^2 + 20489^2 .

It is a cyclic number.

It is not a de Polignac number, because 725000021 - 2¹⁸ = 724737877 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (725000041) 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, 610706 + ... + 611891.

It is an arithmetic number, because the mean of its divisors is an integer number (181555803).

Almost surely, 2^725000021 is an apocalyptic number.

It is an amenable number.

725000021 is a deficient number, since it is larger than the sum of its proper divisors (1223191).

725000021 is a wasteful number, since it uses less digits than its factorization.

725000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1223190.

The product of its (nonzero) digits is 140, while the sum is 17.

The square root of 725000021 is about 26925.8244256327. The cubic root of 725000021 is about 898.3508982453.

Adding to 725000021 its reverse (120000527), we get a palindrome (845000548).

The spelling of 725000021 in words is "seven hundred twenty-five million, twenty-one", and thus it is an aban number.