21661351032145 has 16 divisors (see below), whose sum is σ = 29849134438080. Its totient is φ = 14924567217600.

The previous prime is 21661351032133. The next prime is 21661351032173. The reversal of 21661351032145 is 54123015316612.

It is not a de Polignac number, because 21661351032145 - 2²¹ = 21661348934993 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21661351032098 and 21661351032107.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10364281746 + ... + 10364283835.

It is an arithmetic number, because the mean of its divisors is an integer number (1865570902380).

Almost surely, 2^{21661351032145} is an apocalyptic number.

It is an amenable number.

21661351032145 is a deficient number, since it is larger than the sum of its proper divisors (8187783405935).

21661351032145 is a wasteful number, since it uses less digits than its factorization.

21661351032145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20728565616.

The product of its (nonzero) digits is 129600, while the sum is 40.

Adding to 21661351032145 its reverse (54123015316612), we get a palindrome (75784366348757).

The spelling of 21661351032145 in words is "twenty-one trillion, six hundred sixty-one billion, three hundred fifty-one million, thirty-two thousand, one hundred forty-five".