21920985451 has 4 divisors (see below), whose sum is σ = 21921282400. Its totient is φ = 21920688504.

The previous prime is 21920985433. The next prime is 21920985469. The reversal of 21920985451 is 15458902912.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is an interprime number because it is at equal distance from previous prime (21920985433) and next prime (21920985469).

It is a cyclic number.

It is not a de Polignac number, because 21920985451 - 2⁷ = 21920985323 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21920995451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 57565 + ... + 217153.

It is an arithmetic number, because the mean of its divisors is an integer number (5480320600).

Almost surely, 2^21920985451 is an apocalyptic number.

21920985451 is a deficient number, since it is larger than the sum of its proper divisors (296949).

21920985451 is a wasteful number, since it uses less digits than its factorization.

21920985451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 296948.

The product of its (nonzero) digits is 259200, while the sum is 46.

The spelling of 21920985451 in words is "twenty-one billion, nine hundred twenty million, nine hundred eighty-five thousand, four hundred fifty-one".