21040435501 has 4 divisors (see below), whose sum is σ = 21044759904. Its totient is φ = 21036111100.

The previous prime is 21040435487. The next prime is 21040435513. The reversal of 21040435501 is 10553404012.

It is a happy number.

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 21040435501 - 2¹⁷ = 21040304429 is a prime.

It is a super-2 number, since 2×21040435501² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21040435561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2154895 + ... + 2164636.

It is an arithmetic number, because the mean of its divisors is an integer number (5261189976).

Almost surely, 2^21040435501 is an apocalyptic number.

It is an amenable number.

21040435501 is a deficient number, since it is larger than the sum of its proper divisors (4324403).

21040435501 is an equidigital number, since it uses as much as digits as its factorization.

21040435501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4324402.

The product of its (nonzero) digits is 2400, while the sum is 25.

Adding to 21040435501 its reverse (10553404012), we get a palindrome (31593839513).

The spelling of 21040435501 in words is "twenty-one billion, forty million, four hundred thirty-five thousand, five hundred one".