21378881607 has 32 divisors (see below), whose sum is σ = 31016390400. Its totient is φ = 13043778048.

The previous prime is 21378881597. The next prime is 21378881627. The reversal of 21378881607 is 70618887312.

It is not a de Polignac number, because 21378881607 - 2⁴ = 21378881591 is a prime.

It is a super-2 number, since 2×21378881607² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a self number, because there is not a number n which added to its sum of digits gives 21378881607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21378881627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5317444 + ... + 5321462.

It is an arithmetic number, because the mean of its divisors is an integer number (969262200).

Almost surely, 2^21378881607 is an apocalyptic number.

21378881607 is a deficient number, since it is larger than the sum of its proper divisors (9637508793).

21378881607 is a wasteful number, since it uses less digits than its factorization.

21378881607 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6895.

The product of its (nonzero) digits is 903168, while the sum is 51.

It can be divided in two parts, 21 and 378881607, that added together give a triangular number (378881628 = T₂₇₅₂₇).

The spelling of 21378881607 in words is "twenty-one billion, three hundred seventy-eight million, eight hundred eighty-one thousand, six hundred seven".