21580997949 has 24 divisors (see below), whose sum is σ = 36157509440. Its totient is φ = 12147936768.

The previous prime is 21580997891. The next prime is 21580997959. The reversal of 21580997949 is 94979908512.

21580997949 is a `hidden beast` number, since 2 + 1 + 580 + 9 + 9 + 7 + 9 + 49 = 666.

It is not a de Polignac number, because 21580997949 - 2⁸ = 21580997693 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21580997959) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2552164 + ... + 2560605.

Almost surely, 2^21580997949 is an apocalyptic number.

It is an amenable number.

21580997949 is a deficient number, since it is larger than the sum of its proper divisors (14576511491).

21580997949 is a wasteful number, since it uses less digits than its factorization.

21580997949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5112849 (or 5112846 counting only the distinct ones).

The product of its (nonzero) digits is 14696640, while the sum is 63.

The spelling of 21580997949 in words is "twenty-one billion, five hundred eighty million, nine hundred ninety-seven thousand, nine hundred forty-nine".