21521423511 has 24 divisors (see below), whose sum is σ = 36027823104. Its totient is φ = 12124743120.

The previous prime is 21521423509. The next prime is 21521423629. The reversal of 21521423511 is 11532412512.

It is a happy number.

21521423511 is a `hidden beast` number, since 2 + 1 + 5 + 2 + 142 + 3 + 511 = 666.

It is not a de Polignac number, because 21521423511 - 2¹ = 21521423509 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521223511) 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 23 ways as a sum of consecutive naturals, for example, 2401231 + ... + 2410176.

It is an arithmetic number, because the mean of its divisors is an integer number (1501159296).

Almost surely, 2^21521423511 is an apocalyptic number.

21521423511 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21521423511 is a deficient number, since it is larger than the sum of its proper divisors (14506399593).

21521423511 is a wasteful number, since it uses less digits than its factorization.

21521423511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4811491 (or 4811488 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The spelling of 21521423511 in words is "twenty-one billion, five hundred twenty-one million, four hundred twenty-three thousand, five hundred eleven".