21155503253 has 4 divisors (see below), whose sum is σ = 21163426368. Its totient is φ = 21147580140.

The previous prime is 21155503231. The next prime is 21155503261. The reversal of 21155503253 is 35230555112.

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 21155503253 - 2¹⁶ = 21155437717 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 (21155503153) 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, 3957551 + ... + 3962892.

It is an arithmetic number, because the mean of its divisors is an integer number (5290856592).

Almost surely, 2^21155503253 is an apocalyptic number.

It is an amenable number.

21155503253 is a deficient number, since it is larger than the sum of its proper divisors (7923115).

21155503253 is an equidigital number, since it uses as much as digits as its factorization.

21155503253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7923114.

The product of its (nonzero) digits is 22500, while the sum is 32.

The spelling of 21155503253 in words is "twenty-one billion, one hundred fifty-five million, five hundred three thousand, two hundred fifty-three".