21121506263 has 18 divisors (see below), whose sum is σ = 25139461032. Its totient is φ = 17724323760.

The previous prime is 21121506253. The next prime is 21121506317. The reversal of 21121506263 is 36260512112.

It is not a de Polignac number, because 21121506263 - 2¹⁶ = 21121440727 is a prime.

It is a super-2 number, since 2×21121506263² (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 (21121506223) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 495995 + ... + 536892.

It is an arithmetic number, because the mean of its divisors is an integer number (1396636724).

Almost surely, 2^21121506263 is an apocalyptic number.

21121506263 is a deficient number, since it is larger than the sum of its proper divisors (4017954769).

21121506263 is a wasteful number, since it uses less digits than its factorization.

21121506263 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1032935 (or 1032911 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 29.

The spelling of 21121506263 in words is "twenty-one billion, one hundred twenty-one million, five hundred six thousand, two hundred sixty-three".