21437378553 has 4 divisors (see below), whose sum is σ = 28583171408. Its totient is φ = 14291585700.

The previous prime is 21437378507. The next prime is 21437378561. The reversal of 21437378553 is 35587373412.

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 not a de Polignac number, because 21437378553 - 2¹⁰ = 21437377529 is a prime.

It is a super-2 number, since 2×21437378553² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21437378563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3572896423 + ... + 3572896428.

It is an arithmetic number, because the mean of its divisors is an integer number (7145792852).

Almost surely, 2^21437378553 is an apocalyptic number.

It is an amenable number.

21437378553 is a deficient number, since it is larger than the sum of its proper divisors (7145792855).

21437378553 is an equidigital number, since it uses as much as digits as its factorization.

21437378553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7145792854.

The product of its digits is 2116800, while the sum is 48.

The spelling of 21437378553 in words is "twenty-one billion, four hundred thirty-seven million, three hundred seventy-eight thousand, five hundred fifty-three".