21719250981 has 40 divisors (see below), whose sum is σ = 34277886720. Its totient is φ = 13682686752.

The previous prime is 21719250967. The next prime is 21719250991. The reversal of 21719250981 is 18905291712.

It is not a de Polignac number, because 21719250981 - 2³¹ = 19571767333 is a prime.

It is a super-2 number, since 2×21719250981² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21719250961) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 12040 + ... + 208766.

It is an arithmetic number, because the mean of its divisors is an integer number (856947168).

Almost surely, 2^21719250981 is an apocalyptic number.

It is an amenable number.

21719250981 is a deficient number, since it is larger than the sum of its proper divisors (12558635739).

21719250981 is a wasteful number, since it uses less digits than its factorization.

21719250981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196815 (or 196806 counting only the distinct ones).

The product of its (nonzero) digits is 90720, while the sum is 45.

The spelling of 21719250981 in words is "twenty-one billion, seven hundred nineteen million, two hundred fifty thousand, nine hundred eighty-one".