915725021 has 4 divisors (see below), whose sum is σ = 915839100. Its totient is φ = 915610944.

The previous prime is 915725011. The next prime is 915725029. The reversal of 915725021 is 120527519.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 120527519 = 7 ⋅17218217.

It can be written as a sum of positive squares in 2 ways, for example, as 790396996 + 125328025 = 28114^2 + 11195^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-915725021 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 (915725029) 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, 44006 + ... + 61383.

It is an arithmetic number, because the mean of its divisors is an integer number (228959775).

Almost surely, 2^915725021 is an apocalyptic number.

It is an amenable number.

915725021 is a deficient number, since it is larger than the sum of its proper divisors (114079).

915725021 is a wasteful number, since it uses less digits than its factorization.

915725021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114078.

The product of its (nonzero) digits is 6300, while the sum is 32.

The square root of 915725021 is about 30260.9487789131. The cubic root of 915725021 is about 971.0800387122.

The spelling of 915725021 in words is "nine hundred fifteen million, seven hundred twenty-five thousand, twenty-one".