21257642 has 16 divisors (see below), whose sum is σ = 36607680. Its totient is φ = 9068928.

The previous prime is 21257581. The next prime is 21257651. The reversal of 21257642 is 24675212.

It is a happy 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, 167 + ... + 6522.

It is an arithmetic number, because the mean of its divisors is an integer number (2287980).

Almost surely, 2^21257642 is an apocalyptic number.

21257642 is a deficient number, since it is larger than the sum of its proper divisors (15350038).

21257642 is a wasteful number, since it uses less digits than its factorization.

21257642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6925.

The product of its digits is 6720, while the sum is 29.

The square root of 21257642 is about 4610.6010454170. The cubic root of 21257642 is about 277.0161120492.

It can be divided in two parts, 2125764 and 2, that multiplied together give a cube (4251528 = 162³).

The spelling of 21257642 in words is "twenty-one million, two hundred fifty-seven thousand, six hundred forty-two".