21405456613 has 4 divisors (see below), whose sum is σ = 21676411840. Its totient is φ = 21134501388.

The previous prime is 21405456607. The next prime is 21405456659. The reversal of 21405456613 is 31665450412.

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 21405456613 - 2¹⁷ = 21405325541 is a prime.

It is a super-2 number, since 2×21405456613² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21405756613) 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, 135477495 + ... + 135477652.

It is an arithmetic number, because the mean of its divisors is an integer number (5419102960).

Almost surely, 2^21405456613 is an apocalyptic number.

It is an amenable number.

21405456613 is a deficient number, since it is larger than the sum of its proper divisors (270955227).

21405456613 is an equidigital number, since it uses as much as digits as its factorization.

21405456613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270955226.

The product of its (nonzero) digits is 86400, while the sum is 37.

The spelling of 21405456613 in words is "twenty-one billion, four hundred five million, four hundred fifty-six thousand, six hundred thirteen".