21545756 has 12 divisors (see below), whose sum is σ = 39344592. Its totient is φ = 10304448.

The previous prime is 21545723. The next prime is 21545759. The reversal of 21545756 is 65754512.

It is a super-2 number, since 2×21545756² = 928439203223072, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21545759) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 117005 + ... + 117188.

It is an arithmetic number, because the mean of its divisors is an integer number (3278716).

Almost surely, 2^21545756 is an apocalyptic number.

It is an amenable number.

21545756 is a deficient number, since it is larger than the sum of its proper divisors (17798836).

21545756 is a wasteful number, since it uses less digits than its factorization.

21545756 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 234220 (or 234218 counting only the distinct ones).

The product of its digits is 42000, while the sum is 35.

The square root of 21545756 is about 4641.7406217926. The cubic root of 21545756 is about 278.2620064959.

The spelling of 21545756 in words is "twenty-one million, five hundred forty-five thousand, seven hundred fifty-six".