1025815661 has 4 divisors (see below), whose sum is σ = 1104724572. Its totient is φ = 946906752.

The previous prime is 1025815657. The next prime is 1025815667. The reversal of 1025815661 is 1665185201.

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: 1665185201 = 331 ⋅5030771.

It can be written as a sum of positive squares in 2 ways, for example, as 230857636 + 794958025 = 15194^2 + 28195^2 .

It is a cyclic number.

It is not a de Polignac number, because 1025815661 - 2² = 1025815657 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 (1025815667) 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, 39454436 + ... + 39454461.

It is an arithmetic number, because the mean of its divisors is an integer number (276181143).

Almost surely, 2^1025815661 is an apocalyptic number.

It is an amenable number.

1025815661 is a deficient number, since it is larger than the sum of its proper divisors (78908911).

1025815661 is an equidigital number, since it uses as much as digits as its factorization.

1025815661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78908910.

The product of its (nonzero) digits is 14400, while the sum is 35.

The square root of 1025815661 is about 32028.3571386358. The cubic root of 1025815661 is about 1008.5322146026.

The spelling of 1025815661 in words is "one billion, twenty-five million, eight hundred fifteen thousand, six hundred sixty-one".