21997181044 has 6 divisors (see below), whose sum is σ = 38495066834. Its totient is φ = 10998590520.

The previous prime is 21997181029. The next prime is 21997181057. The reversal of 21997181044 is 44018179912.

It can be written as a sum of positive squares in only one way, i.e., 15361123600 + 6636057444 = 123940^2 + 81462^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21997180985 and 21997181003.

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, 2749647627 + ... + 2749647634.

Almost surely, 2^21997181044 is an apocalyptic number.

It is an amenable number.

21997181044 is a deficient number, since it is larger than the sum of its proper divisors (16497885790).

21997181044 is a wasteful number, since it uses less digits than its factorization.

21997181044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5499295265 (or 5499295263 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 46.

The spelling of 21997181044 in words is "twenty-one billion, nine hundred ninety-seven million, one hundred eighty-one thousand, forty-four".