21878045 has 8 divisors (see below), whose sum is σ = 30004224. Its totient is φ = 15002064.

The previous prime is 21877951. The next prime is 21878047. The reversal of 21878045 is 54087812.

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

It is not a de Polignac number, because 21878045 - 2⁸ = 21877789 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (35), and also a Moran number because the ratio is a prime number: 625087 = 21878045 / (2 + 1 + 8 + 7 + 8 + 0 + 4 + 5).

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21877996 and 21878014.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21878047) 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, 312509 + ... + 312578.

It is an arithmetic number, because the mean of its divisors is an integer number (3750528).

Almost surely, 2^21878045 is an apocalyptic number.

It is an amenable number.

21878045 is a deficient number, since it is larger than the sum of its proper divisors (8126179).

21878045 is an equidigital number, since it uses as much as digits as its factorization.

21878045 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 625099.

The product of its (nonzero) digits is 17920, while the sum is 35.

The square root of 21878045 is about 4677.3972463326. The cubic root of 21878045 is about 279.6852117100.

The spelling of 21878045 in words is "twenty-one million, eight hundred seventy-eight thousand, forty-five".