21378897 has 24 divisors (see below), whose sum is σ = 32390176. Its totient is φ = 14090112.

The previous prime is 21378883. The next prime is 21378899. The reversal of 21378897 is 79887312.

It is not a de Polignac number, because 21378897 - 2⁸ = 21378641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21378899) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 23118 + ... + 24024.

Almost surely, 2^21378897 is an apocalyptic number.

21378897 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21378897 is a deficient number, since it is larger than the sum of its proper divisors (11011279).

21378897 is an frugal number, since it uses more digits than its factorization.

21378897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1019 (or 1007 counting only the distinct ones).

The product of its digits is 169344, while the sum is 45.

The square root of 21378897 is about 4623.7319342713. The cubic root of 21378897 is about 277.5418198478.

The spelling of 21378897 in words is "twenty-one million, three hundred seventy-eight thousand, eight hundred ninety-seven".