21408401523 has 8 divisors (see below), whose sum is σ = 28582956288. Its totient is φ = 14253057224.

The previous prime is 21408401513. The next prime is 21408401543. The reversal of 21408401523 is 32510480412.

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

It is a cyclic number.

It is not a de Polignac number, because 21408401523 - 2⁵ = 21408401491 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21408401513) 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, 4800015 + ... + 4804472.

It is an arithmetic number, because the mean of its divisors is an integer number (3572869536).

Almost surely, 2^21408401523 is an apocalyptic number.

21408401523 is a deficient number, since it is larger than the sum of its proper divisors (7174554765).

21408401523 is an equidigital number, since it uses as much as digits as its factorization.

21408401523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9605233.

The product of its (nonzero) digits is 7680, while the sum is 30.

Adding to 21408401523 its reverse (32510480412), we get a palindrome (53918881935).

The spelling of 21408401523 in words is "twenty-one billion, four hundred eight million, four hundred one thousand, five hundred twenty-three".