21512413251 has 24 divisors (see below), whose sum is σ = 35519088384. Its totient is φ = 12290546160.

The previous prime is 21512413249. The next prime is 21512413253. The reversal of 21512413251 is 15231421512.

It is a happy number.

21512413251 is a `hidden beast` number, since 215 + 12 + 413 + 25 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (21512413249) and next prime (21512413253).

It is not a de Polignac number, because 21512413251 - 2¹ = 21512413249 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21512413253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 350290 + ... + 407096.

It is an arithmetic number, because the mean of its divisors is an integer number (1479962016).

Almost surely, 2^21512413251 is an apocalyptic number.

21512413251 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21512413251 is a deficient number, since it is larger than the sum of its proper divisors (14006675133).

21512413251 is a wasteful number, since it uses less digits than its factorization.

21512413251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62831 (or 62828 counting only the distinct ones).

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

Adding to 21512413251 its reverse (15231421512), we get a palindrome (36743834763).

The spelling of 21512413251 in words is "twenty-one billion, five hundred twelve million, four hundred thirteen thousand, two hundred fifty-one".