21229617780 has 384 divisors, whose sum is σ = 81316085760. Its totient is φ = 4491210240.

The previous prime is 21229617767. The next prime is 21229617791. The reversal of 21229617780 is 8771692212.

It is a happy number.

21229617780 is a `hidden beast` number, since 2 + 1 + 2 + 29 + 617 + 7 + 8 + 0 = 666.

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 polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 2691202 + ... + 2699078.

It is an arithmetic number, because the mean of its divisors is an integer number (211760640).

Almost surely, 2^21229617780 is an apocalyptic number.

21229617780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21229617780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40658042880).

21229617780 is an abundant number, since it is smaller than the sum of its proper divisors (60086467980).

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

21229617780 is a wasteful number, since it uses less digits than its factorization.

21229617780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7956 (or 7948 counting only the distinct ones).

The product of its (nonzero) digits is 169344, while the sum is 45.

The spelling of 21229617780 in words is "twenty-one billion, two hundred twenty-nine million, six hundred seventeen thousand, seven hundred eighty".