21347657 has 4 divisors (see below), whose sum is σ = 22275840. Its totient is φ = 20419476.

The previous prime is 21347653. The next prime is 21347701. The reversal of 21347657 is 75674312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21347657 - 2² = 21347653 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21347653) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 464057 + ... + 464102.

It is an arithmetic number, because the mean of its divisors is an integer number (5568960).

Almost surely, 2^21347657 is an apocalyptic number.

It is an amenable number.

21347657 is a deficient number, since it is larger than the sum of its proper divisors (928183).

21347657 is an equidigital number, since it uses as much as digits as its factorization.

21347657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 928182.

The product of its digits is 35280, while the sum is 35.

The square root of 21347657 is about 4620.3524757317. The cubic root of 21347657 is about 277.4065675769.

The spelling of 21347657 in words is "twenty-one million, three hundred forty-seven thousand, six hundred fifty-seven".