21057742 has 16 divisors (see below), whose sum is σ = 34025472. Its totient is φ = 9745560.

The previous prime is 21057731. The next prime is 21057763. The reversal of 21057742 is 24775012.

It is a self number, because there is not a number n which added to its sum of digits gives 21057742.

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, 5958 + ... + 8809.

It is an arithmetic number, because the mean of its divisors is an integer number (2126592).

Almost surely, 2^21057742 is an apocalyptic number.

21057742 is a deficient number, since it is larger than the sum of its proper divisors (12967730).

21057742 is a wasteful number, since it uses less digits than its factorization.

21057742 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14823.

The product of its (nonzero) digits is 3920, while the sum is 28.

The square root of 21057742 is about 4588.8715388426. The cubic root of 21057742 is about 276.1450525783.

The spelling of 21057742 in words is "twenty-one million, fifty-seven thousand, seven hundred forty-two".