21790454989 has 4 divisors (see below), whose sum is σ = 21809964124. Its totient is φ = 21770945856.

The previous prime is 21790454977. The next prime is 21790455017. The reversal of 21790454989 is 98945409712.

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

It can be written as a sum of positive squares in 2 ways, for example, as 11248299364 + 10542155625 = 106058^2 + 102675^2 .

It is a cyclic number.

It is not a de Polignac number, because 21790454989 - 2²¹ = 21788357837 is a prime.

It is a super-3 number, since 3×21790454989³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21790254989) 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, 9752892 + ... + 9755125.

It is an arithmetic number, because the mean of its divisors is an integer number (5452491031).

Almost surely, 2^21790454989 is an apocalyptic number.

It is an amenable number.

21790454989 is a deficient number, since it is larger than the sum of its proper divisors (19509135).

21790454989 is a wasteful number, since it uses less digits than its factorization.

21790454989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19509134.

The product of its (nonzero) digits is 6531840, while the sum is 58.

The spelling of 21790454989 in words is "twenty-one billion, seven hundred ninety million, four hundred fifty-four thousand, nine hundred eighty-nine".