21660401531505 has 48 divisors (see below), whose sum is σ = 38336300154432. Its totient is φ = 10435120924800.

The previous prime is 21660401531477. The next prime is 21660401531507. The reversal of 21660401531505 is 50513510406612.

It is not a de Polignac number, because 21660401531505 - 2⁶ = 21660401531441 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21660401531507) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 37721751 + ... + 38291660.

It is an arithmetic number, because the mean of its divisors is an integer number (798672919884).

Almost surely, 2^{21660401531505} is an apocalyptic number.

It is an amenable number.

21660401531505 is a deficient number, since it is larger than the sum of its proper divisors (16675898622927).

21660401531505 is a wasteful number, since it uses less digits than its factorization.

21660401531505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76013598 (or 76013587 counting only the distinct ones).

The product of its (nonzero) digits is 108000, while the sum is 39.

The spelling of 21660401531505 in words is "twenty-one trillion, six hundred sixty billion, four hundred one million, five hundred thirty-one thousand, five hundred five".