21742557 has 8 divisors (see below), whose sum is σ = 29256480. Its totient is φ = 14361840.

The previous prime is 21742493. The next prime is 21742571. The reversal of 21742557 is 75524712.

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

It is not a de Polignac number, because 21742557 - 2⁶ = 21742493 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21742577) 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, 32919 + ... + 33572.

It is an arithmetic number, because the mean of its divisors is an integer number (3657060).

Almost surely, 2^21742557 is an apocalyptic number.

It is an amenable number.

21742557 is a deficient number, since it is larger than the sum of its proper divisors (7513923).

21742557 is a wasteful number, since it uses less digits than its factorization.

21742557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66603.

The product of its digits is 19600, while the sum is 33.

The square root of 21742557 is about 4662.8914849050. The cubic root of 21742557 is about 279.1066639092.

The spelling of 21742557 in words is "twenty-one million, seven hundred forty-two thousand, five hundred fifty-seven".