21571620377 has 8 divisors (see below), whose sum is σ = 21870405480. Its totient is φ = 21272924160.

The previous prime is 21571620353. The next prime is 21571620407. The reversal of 21571620377 is 77302617512.

It can be written as a sum of positive squares in 4 ways, for example, as 701773081 + 20869847296 = 26491^2 + 144464^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21571620377 - 2¹⁴ = 21571603993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21571620337) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 577649 + ... + 613857.

It is an arithmetic number, because the mean of its divisors is an integer number (2733800685).

Almost surely, 2^21571620377 is an apocalyptic number.

It is an amenable number.

21571620377 is a deficient number, since it is larger than the sum of its proper divisors (298785103).

21571620377 is an equidigital number, since it uses as much as digits as its factorization.

21571620377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44443.

The product of its (nonzero) digits is 123480, while the sum is 41.

The spelling of 21571620377 in words is "twenty-one billion, five hundred seventy-one million, six hundred twenty thousand, three hundred seventy-seven".