21661006239 has 6 divisors (see below), whose sum is σ = 31288120136. Its totient is φ = 14440670820.

The previous prime is 21661006223. The next prime is 21661006261. The reversal of 21661006239 is 93260016612.

It is a happy number.

21661006239 is a `hidden beast` number, since 2 + 1 + 6 + 610 + 0 + 6 + 2 + 39 = 666.

It is not a de Polignac number, because 21661006239 - 2⁴ = 21661006223 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 (21661006039) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1203389227 + ... + 1203389244.

Almost surely, 2^21661006239 is an apocalyptic number.

21661006239 is a deficient number, since it is larger than the sum of its proper divisors (9627113897).

21661006239 is a wasteful number, since it uses less digits than its factorization.

21661006239 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2406778477 (or 2406778474 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The spelling of 21661006239 in words is "twenty-one billion, six hundred sixty-one million, six thousand, two hundred thirty-nine".