21170739780 has 72 divisors (see below), whose sum is σ = 64396987200. Its totient is φ = 5629787712.

The previous prime is 21170739769. The next prime is 21170739823. The reversal of 21170739780 is 8793707112.

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

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 99190 + ... + 228429.

It is an arithmetic number, because the mean of its divisors is an integer number (894402600).

Almost surely, 2^21170739780 is an apocalyptic number.

21170739780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21170739780 is an abundant number, since it is smaller than the sum of its proper divisors (43226247420).

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

21170739780 is a wasteful number, since it uses less digits than its factorization.

21170739780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 327993 (or 327988 counting only the distinct ones).

The product of its (nonzero) digits is 148176, while the sum is 45.

The spelling of 21170739780 in words is "twenty-one billion, one hundred seventy million, seven hundred thirty-nine thousand, seven hundred eighty".