21249438889780 has 12 divisors (see below), whose sum is σ = 44623821668580. Its totient is φ = 8499775555904.

The previous prime is 21249438889753. The next prime is 21249438889787. The reversal of 21249438889780 is 8798883494212.

It can be written as a sum of positive squares in 2 ways, for example, as 14283365483556 + 6966073406224 = 3779334^2 + 2639332^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21249438889787) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 531235972225 + ... + 531235972264.

It is an arithmetic number, because the mean of its divisors is an integer number (3718651805715).

Almost surely, 2^{21249438889780} is an apocalyptic number.

21249438889780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21249438889780 is an abundant number, since it is smaller than the sum of its proper divisors (23374382778800).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21249438889780 is a wasteful number, since it uses less digits than its factorization.

21249438889780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1062471944498 (or 1062471944496 counting only the distinct ones).

The product of its (nonzero) digits is 445906944, while the sum is 73.

The spelling of 21249438889780 in words is "twenty-one trillion, two hundred forty-nine billion, four hundred thirty-eight million, eight hundred eighty-nine thousand, seven hundred eighty".