21661351032404 has 6 divisors (see below), whose sum is σ = 37907364306714. Its totient is φ = 10830675516200.

The previous prime is 21661351032371. The next prime is 21661351032481. The reversal of 21661351032404 is 40423015316612.

It can be written as a sum of positive squares in only one way, i.e., 13374160984900 + 8287190047504 = 3657070^2 + 2878748^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2707668879047 + ... + 2707668879054.

It is an arithmetic number, because the mean of its divisors is an integer number (6317894051119).

Almost surely, 2^{21661351032404} is an apocalyptic number.

It is an amenable number.

21661351032404 is a deficient number, since it is larger than the sum of its proper divisors (16246013274310).

21661351032404 is a wasteful number, since it uses less digits than its factorization.

21661351032404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5415337758105 (or 5415337758103 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 38.

The spelling of 21661351032404 in words is "twenty-one trillion, six hundred sixty-one billion, three hundred fifty-one million, thirty-two thousand, four hundred four".