21378104991 has 12 divisors (see below), whose sum is σ = 30881136832. Its totient is φ = 14251307616.

The previous prime is 21378104987. The next prime is 21378105029. The reversal of 21378104991 is 19940187312.

It is not a de Polignac number, because 21378104991 - 2² = 21378104987 is a prime.

It is a super-2 number, since 2×21378104991² (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 (21378103991) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 152850 + ... + 257136.

Almost surely, 2^21378104991 is an apocalyptic number.

21378104991 is a deficient number, since it is larger than the sum of its proper divisors (9503031841).

21378104991 is a wasteful number, since it uses less digits than its factorization.

21378104991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127070 (or 127067 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 45.

The spelling of 21378104991 in words is "twenty-one billion, three hundred seventy-eight million, one hundred four thousand, nine hundred ninety-one".