21553657601 has 4 divisors (see below), whose sum is σ = 24632751552. Its totient is φ = 18474563652.

The previous prime is 21553657583. The next prime is 21553657603. The reversal of 21553657601 is 10675635512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21553657601 - 2⁶ = 21553657537 is a prime.

It is a super-2 number, since 2×21553657601² (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 (21553657603) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1539546965 + ... + 1539546978.

It is an arithmetic number, because the mean of its divisors is an integer number (6158187888).

Almost surely, 2^21553657601 is an apocalyptic number.

It is an amenable number.

21553657601 is a deficient number, since it is larger than the sum of its proper divisors (3079093951).

21553657601 is an equidigital number, since it uses as much as digits as its factorization.

21553657601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3079093950.

The product of its (nonzero) digits is 189000, while the sum is 41.

The spelling of 21553657601 in words is "twenty-one billion, five hundred fifty-three million, six hundred fifty-seven thousand, six hundred one".