21399653 has 8 divisors (see below), whose sum is σ = 23976480. Its totient is φ = 18928080.

The previous prime is 21399649. The next prime is 21399659. The reversal of 21399653 is 35699312.

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 21399653 - 2² = 21399649 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21399659) 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, 25883 + ... + 26696.

It is an arithmetic number, because the mean of its divisors is an integer number (2997060).

Almost surely, 2^21399653 is an apocalyptic number.

It is an amenable number.

21399653 is a deficient number, since it is larger than the sum of its proper divisors (2576827).

21399653 is a wasteful number, since it uses less digits than its factorization.

21399653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52627.

The product of its digits is 43740, while the sum is 38.

The square root of 21399653 is about 4625.9758970405. The cubic root of 21399653 is about 277.6316092438.

The spelling of 21399653 in words is "twenty-one million, three hundred ninety-nine thousand, six hundred fifty-three".