21523203412 has 24 divisors (see below), whose sum is σ = 39027701160. Its totient is φ = 10373637120.

The previous prime is 21523203407. The next prime is 21523203431. The reversal of 21523203412 is 21430232512.

It can be written as a sum of positive squares in 4 ways, for example, as 44542276 + 21478661136 = 6674^2 + 146556^2 .

It is a super-2 number, since 2×21523203412² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 78789 + ... + 221932.

It is an arithmetic number, because the mean of its divisors is an integer number (1626154215).

Almost surely, 2^21523203412 is an apocalyptic number.

It is an amenable number.

21523203412 is a deficient number, since it is larger than the sum of its proper divisors (17504497748).

21523203412 is a wasteful number, since it uses less digits than its factorization.

21523203412 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 301371 (or 301369 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 25.

Adding to 21523203412 its reverse (21430232512), we get a palindrome (42953435924).

The spelling of 21523203412 in words is "twenty-one billion, five hundred twenty-three million, two hundred three thousand, four hundred twelve".