21202121451 has 32 divisors (see below), whose sum is σ = 34104983040. Its totient is φ = 11445249024.

The previous prime is 21202121443. The next prime is 21202121453. The reversal of 21202121451 is 15412120212.

It is not a de Polignac number, because 21202121451 - 2³ = 21202121443 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21202121453) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 65581 + ... + 216113.

It is an arithmetic number, because the mean of its divisors is an integer number (1065780720).

Almost surely, 2^21202121451 is an apocalyptic number.

21202121451 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21202121451 is a deficient number, since it is larger than the sum of its proper divisors (12902861589).

21202121451 is a wasteful number, since it uses less digits than its factorization.

21202121451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150915.

The product of its (nonzero) digits is 320, while the sum is 21.

Adding to 21202121451 its reverse (15412120212), we get a palindrome (36614241663).

The spelling of 21202121451 in words is "twenty-one billion, two hundred two million, one hundred twenty-one thousand, four hundred fifty-one".