21406774637 has 4 divisors (see below), whose sum is σ = 21424810176. Its totient is φ = 21388739100.

The previous prime is 21406774553. The next prime is 21406774639. The reversal of 21406774637 is 73647760412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21406774637 - 2²⁰ = 21405726061 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21406774591 and 21406774600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21406774639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9015989 + ... + 9018362.

It is an arithmetic number, because the mean of its divisors is an integer number (5356202544).

Almost surely, 2^21406774637 is an apocalyptic number.

It is an amenable number.

21406774637 is a deficient number, since it is larger than the sum of its proper divisors (18035539).

21406774637 is a wasteful number, since it uses less digits than its factorization.

21406774637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18035538.

The product of its (nonzero) digits is 1185408, while the sum is 47.

The spelling of 21406774637 in words is "twenty-one billion, four hundred six million, seven hundred seventy-four thousand, six hundred thirty-seven".