981960101721 has 9 divisors (see below), whose sum is σ = 1418391107679. Its totient is φ = 654638085936.

The previous prime is 981960101713. The next prime is 981960101777. The reversal of 981960101721 is 127101069189.

It is a happy number.

The square root of 981960101721 is 990939.

It is a perfect power (a square), and thus also a powerful number.

981960101721 is a `hidden beast` number, since 9 + 8 + 1 + 9 + 601 + 0 + 17 + 21 = 666.

It can be written as a sum of positive squares in only one way, i.e., 464803515225 + 517156586496 = 681765^2 + 719136^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 981960101721 - 2³ = 981960101713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (981960109721) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2807661 + ... + 3137973.

Almost surely, 2^981960101721 is an apocalyptic number.

981960101721 is the 990939-th square number.

981960101721 is the 495470-th centered octagonal number.

It is an amenable number.

981960101721 is a deficient number, since it is larger than the sum of its proper divisors (436431005958).

981960101721 is an frugal number, since it uses more digits than its factorization.

981960101721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 660632 (or 330316 counting only the distinct ones).

The product of its (nonzero) digits is 54432, while the sum is 45.

It can be divided in two parts, 981960 and 101721, that added together give a square (1083681 = 1041²).

The spelling of 981960101721 in words is "nine hundred eighty-one billion, nine hundred sixty million, one hundred one thousand, seven hundred twenty-one".