21307403551 has 8 divisors (see below), whose sum is σ = 24659563520. Its totient is φ = 18032304888.

The previous prime is 21307403539. The next prime is 21307403561. The reversal of 21307403551 is 15530470312.

It is a happy number.

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 21307403551 - 2²³ = 21299014943 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21307403501) 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, 19264731 + ... + 19265836.

It is an arithmetic number, because the mean of its divisors is an integer number (3082445440).

Almost surely, 2^21307403551 is an apocalyptic number.

21307403551 is a deficient number, since it is larger than the sum of its proper divisors (3352159969).

21307403551 is an equidigital number, since it uses as much as digits as its factorization.

21307403551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38530653.

The product of its (nonzero) digits is 12600, while the sum is 31.

Adding to 21307403551 its reverse (15530470312), we get a palindrome (36837873863).

The spelling of 21307403551 in words is "twenty-one billion, three hundred seven million, four hundred three thousand, five hundred fifty-one".