21378104987 has 2 divisors, whose sum is σ = 21378104988. Its totient is φ = 21378104986.

The previous prime is 21378104939. The next prime is 21378105029. The reversal of 21378104987 is 78940187312.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21378104987 - 2²² = 21373910683 is a prime.

It is not a weakly prime, because it can be changed into another prime (21378104387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10689052493 + 10689052494.

It is an arithmetic number, because the mean of its divisors is an integer number (10689052494).

Almost surely, 2^21378104987 is an apocalyptic number.

21378104987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21378104987 is an equidigital number, since it uses as much as digits as its factorization.

21378104987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 677376, while the sum is 50.

The spelling of 21378104987 in words is "twenty-one billion, three hundred seventy-eight million, one hundred four thousand, nine hundred eighty-seven".