21202202251 has 4 divisors (see below), whose sum is σ = 21237132352. Its totient is φ = 21167272152.

The previous prime is 21202202249. The next prime is 21202202291. The reversal of 21202202251 is 15220220212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21202202251 - 2¹ = 21202202249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21202202291) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17464140 + ... + 17465353.

It is an arithmetic number, because the mean of its divisors is an integer number (5309283088).

Almost surely, 2^21202202251 is an apocalyptic number.

21202202251 is a deficient number, since it is larger than the sum of its proper divisors (34930101).

21202202251 is an equidigital number, since it uses as much as digits as its factorization.

21202202251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34930100.

The product of its (nonzero) digits is 320, while the sum is 19.

Adding to 21202202251 its reverse (15220220212), we get a palindrome (36422422463).

The spelling of 21202202251 in words is "twenty-one billion, two hundred two million, two hundred two thousand, two hundred fifty-one".