21405356601 has 4 divisors (see below), whose sum is σ = 28540475472. Its totient is φ = 14270237732.

The previous prime is 21405356597. The next prime is 21405356611. The reversal of 21405356601 is 10665350412.

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 21405356601 - 2² = 21405356597 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21405356611) 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, 3567559431 + ... + 3567559436.

It is an arithmetic number, because the mean of its divisors is an integer number (7135118868).

Almost surely, 2^21405356601 is an apocalyptic number.

It is an amenable number.

21405356601 is a deficient number, since it is larger than the sum of its proper divisors (7135118871).

21405356601 is an equidigital number, since it uses as much as digits as its factorization.

21405356601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7135118870.

The product of its (nonzero) digits is 21600, while the sum is 33.

The spelling of 21405356601 in words is "twenty-one billion, four hundred five million, three hundred fifty-six thousand, six hundred one".