21720042669 has 16 divisors (see below), whose sum is σ = 31232283264. Its totient is φ = 13347096000.

The previous prime is 21720042667. The next prime is 21720042719. The reversal of 21720042669 is 96624002712.

It is not a de Polignac number, because 21720042669 - 2¹ = 21720042667 is a prime.

It is a super-2 number, since 2×21720042669² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21720042667) 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, 369897 + ... + 424574.

It is an arithmetic number, because the mean of its divisors is an integer number (1952017704).

Almost surely, 2^21720042669 is an apocalyptic number.

It is an amenable number.

21720042669 is a deficient number, since it is larger than the sum of its proper divisors (9512240595).

21720042669 is a wasteful number, since it uses less digits than its factorization.

21720042669 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 795188.

The product of its (nonzero) digits is 72576, while the sum is 39.

The spelling of 21720042669 in words is "twenty-one billion, seven hundred twenty million, forty-two thousand, six hundred sixty-nine".