21175941780 has 120 divisors (see below), whose sum is σ = 75919713408. Its totient is φ = 4840212672.

The previous prime is 21175941779. The next prime is 21175941803. The reversal of 21175941780 is 8714957112.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 922344 + ... + 945023.

Almost surely, 2^21175941780 is an apocalyptic number.

21175941780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21175941780 is an abundant number, since it is smaller than the sum of its proper divisors (54743771628).

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

21175941780 is a wasteful number, since it uses less digits than its factorization.

21175941780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1867395 (or 1867384 counting only the distinct ones).

The product of its (nonzero) digits is 141120, while the sum is 45.

The spelling of 21175941780 in words is "twenty-one billion, one hundred seventy-five million, nine hundred forty-one thousand, seven hundred eighty".