21406012881 has 8 divisors (see below), whose sum is σ = 31136018784. Its totient is φ = 12973341120.

The previous prime is 21406012877. The next prime is 21406012889. The reversal of 21406012881 is 18821060412.

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

It is not a de Polignac number, because 21406012881 - 2² = 21406012877 is a prime.

It is a super-2 number, since 2×21406012881² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 648667057 = 21406012881 / (2 + 1 + 4 + 0 + 6 + 0 + 1 + 2 + 8 + 8 + 1).

It is not an unprimeable number, because it can be changed into a prime (21406012889) 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, 324333496 + ... + 324333561.

It is an arithmetic number, because the mean of its divisors is an integer number (3892002348).

Almost surely, 2^21406012881 is an apocalyptic number.

It is an amenable number.

21406012881 is a deficient number, since it is larger than the sum of its proper divisors (9730005903).

21406012881 is a wasteful number, since it uses less digits than its factorization.

21406012881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 648667071.

The product of its (nonzero) digits is 6144, while the sum is 33.

The spelling of 21406012881 in words is "twenty-one billion, four hundred six million, twelve thousand, eight hundred eighty-one".