21229617781 has 16 divisors (see below), whose sum is σ = 22018233600. Its totient is φ = 20459275200.

The previous prime is 21229617767. The next prime is 21229617791. The reversal of 21229617781 is 18771692212.

It is a cyclic number.

It is not a de Polignac number, because 21229617781 - 2²³ = 21221229173 is a prime.

It is a super-2 number, since 2×21229617781² (a number of 21 digits) contains 22 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 (21229617701) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 614475 + ... + 648103.

It is an arithmetic number, because the mean of its divisors is an integer number (1376139600).

Almost surely, 2^21229617781 is an apocalyptic number.

It is an amenable number.

21229617781 is a deficient number, since it is larger than the sum of its proper divisors (788615819).

21229617781 is a wasteful number, since it uses less digits than its factorization.

21229617781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33900.

The product of its digits is 169344, while the sum is 46.

The spelling of 21229617781 in words is "twenty-one billion, two hundred twenty-nine million, six hundred seventeen thousand, seven hundred eighty-one".