21542251251 has 8 divisors (see below), whose sum is σ = 28741550800. Its totient is φ = 14352226272.

The previous prime is 21542251249. The next prime is 21542251253. The reversal of 21542251251 is 15215224512.

It is an interprime number because it is at equal distance from previous prime (21542251249) and next prime (21542251253).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21542251251 - 2¹ = 21542251249 is a prime.

It is a super-2 number, since 2×21542251251² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21542251253) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2313220 + ... + 2322513.

It is an arithmetic number, because the mean of its divisors is an integer number (3592693850).

Almost surely, 2^21542251251 is an apocalyptic number.

21542251251 is a deficient number, since it is larger than the sum of its proper divisors (7199299549).

21542251251 is a wasteful number, since it uses less digits than its factorization.

21542251251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4637285.

The product of its digits is 8000, while the sum is 30.

Adding to 21542251251 its reverse (15215224512), we get a palindrome (36757475763).

The spelling of 21542251251 in words is "twenty-one billion, five hundred forty-two million, two hundred fifty-one thousand, two hundred fifty-one".