21406133755 has 4 divisors (see below), whose sum is σ = 25687360512. Its totient is φ = 17124907000.

The previous prime is 21406133737. The next prime is 21406133759. The reversal of 21406133755 is 55733160412.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21406133755 - 2¹³ = 21406125563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21406133759) 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, 2140613371 + ... + 2140613380.

It is an arithmetic number, because the mean of its divisors is an integer number (6421840128).

Almost surely, 2^21406133755 is an apocalyptic number.

21406133755 is a deficient number, since it is larger than the sum of its proper divisors (4281226757).

21406133755 is an equidigital number, since it uses as much as digits as its factorization.

21406133755 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4281226756.

The product of its (nonzero) digits is 75600, while the sum is 37.

The spelling of 21406133755 in words is "twenty-one billion, four hundred six million, one hundred thirty-three thousand, seven hundred fifty-five".