21690455 has 8 divisors (see below), whose sum is σ = 26268000. Its totient is φ = 17192736.

The previous prime is 21690451. The next prime is 21690467. The reversal of 21690455 is 55409612.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21690455 - 2² = 21690451 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21690451) 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, 19355 + ... + 20444.

It is an arithmetic number, because the mean of its divisors is an integer number (3283500).

Almost surely, 2^21690455 is an apocalyptic number.

21690455 is a deficient number, since it is larger than the sum of its proper divisors (4577545).

21690455 is a wasteful number, since it uses less digits than its factorization.

21690455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39913.

The product of its (nonzero) digits is 10800, while the sum is 32.

The square root of 21690455 is about 4657.3012571660. The cubic root of 21690455 is about 278.8835431629.

The spelling of 21690455 in words is "twenty-one million, six hundred ninety thousand, four hundred fifty-five".