21606378977 has 32 divisors (see below), whose sum is σ = 23162388480. Its totient is φ = 20121658560.

The previous prime is 21606378971. The next prime is 21606379001. The reversal of 21606378977 is 77987360612.

It is not a de Polignac number, because 21606378977 - 2³² = 17311411681 is a prime.

It is a super-2 number, since 2×21606378977² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21606378971) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 45107024 + ... + 45107502.

It is an arithmetic number, because the mean of its divisors is an integer number (723824640).

Almost surely, 2^21606378977 is an apocalyptic number.

It is an amenable number.

21606378977 is a deficient number, since it is larger than the sum of its proper divisors (1556009503).

21606378977 is a wasteful number, since it uses less digits than its factorization.

21606378977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1013.

The product of its (nonzero) digits is 5334336, while the sum is 56.

The spelling of 21606378977 in words is "twenty-one billion, six hundred six million, three hundred seventy-eight thousand, nine hundred seventy-seven".