21745101251 has 8 divisors (see below), whose sum is σ = 23092552080. Its totient is φ = 20405242368.

The previous prime is 21745101239. The next prime is 21745101281. The reversal of 21745101251 is 15210154712.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21745101251 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21745101281) 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, 1892081 + ... + 1903538.

It is an arithmetic number, because the mean of its divisors is an integer number (2886569010).

Almost surely, 2^21745101251 is an apocalyptic number.

21745101251 is a deficient number, since it is larger than the sum of its proper divisors (1347450829).

21745101251 is a wasteful number, since it uses less digits than its factorization.

21745101251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3795973.

The product of its (nonzero) digits is 2800, while the sum is 29.

Adding to 21745101251 its reverse (15210154712), we get a palindrome (36955255963).

The spelling of 21745101251 in words is "twenty-one billion, seven hundred forty-five million, one hundred one thousand, two hundred fifty-one".