26215661 has 8 divisors (see below), whose sum is σ = 26721144. Its totient is φ = 25715200.

The previous prime is 26215643. The next prime is 26215669. The reversal of 26215661 is 16651262.

26215661 = 255² + 256² + ... + 456².

It can be written as a sum of positive squares in 4 ways, for example, as 2992900 + 23222761 = 1730^2 + 4819^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 26215661 - 2²² = 22021357 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 (26215669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10265 + ... + 12561.

It is an arithmetic number, because the mean of its divisors is an integer number (3340143).

Almost surely, 2^26215661 is an apocalyptic number.

It is an amenable number.

26215661 is a deficient number, since it is larger than the sum of its proper divisors (505483).

26215661 is a wasteful number, since it uses less digits than its factorization.

26215661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2511.

The product of its digits is 4320, while the sum is 29.

The square root of 26215661 is about 5120.1231430504. The cubic root of 26215661 is about 297.0664484939.

The spelling of 26215661 in words is "twenty-six million, two hundred fifteen thousand, six hundred sixty-one".