21425765 has 8 divisors (see below), whose sum is σ = 26828928. Its totient is φ = 16395280.

The previous prime is 21425759. The next prime is 21425773. The reversal of 21425765 is 56752412.

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

It is not a de Polignac number, because 21425765 - 2¹⁸ = 21163621 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 93041 + ... + 93270.

It is an arithmetic number, because the mean of its divisors is an integer number (3353616).

Almost surely, 2^21425765 is an apocalyptic number.

It is an amenable number.

21425765 is a deficient number, since it is larger than the sum of its proper divisors (5403163).

21425765 is a wasteful number, since it uses less digits than its factorization.

21425765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186339.

The product of its digits is 16800, while the sum is 32.

The square root of 21425765 is about 4628.7973600062. The cubic root of 21425765 is about 277.7444859953.

The spelling of 21425765 in words is "twenty-one million, four hundred twenty-five thousand, seven hundred sixty-five".