21242762781 has 8 divisors (see below), whose sum is σ = 28324405440. Its totient is φ = 14161480992.

The previous prime is 21242762767. The next prime is 21242762789. The reversal of 21242762781 is 18726724212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-21242762781 is a prime.

It is a super-2 number, since 2×21242762781² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21242762789) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 111696 + ... + 234438.

It is an arithmetic number, because the mean of its divisors is an integer number (3540550680).

Almost surely, 2^21242762781 is an apocalyptic number.

It is an amenable number.

21242762781 is a deficient number, since it is larger than the sum of its proper divisors (7081642659).

21242762781 is a wasteful number, since it uses less digits than its factorization.

21242762781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180435.

The product of its digits is 150528, while the sum is 42.

The spelling of 21242762781 in words is "twenty-one billion, two hundred forty-two million, seven hundred sixty-two thousand, seven hundred eighty-one".