21519755 has 16 divisors (see below), whose sum is σ = 26840160. Its totient is φ = 16549632.

The previous prime is 21519727. The next prime is 21519791. The reversal of 21519755 is 55791512.

It is a cyclic number.

It is not a de Polignac number, because 21519755 - 2⁶ = 21519691 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15812 + ... + 17118.

It is an arithmetic number, because the mean of its divisors is an integer number (1677510).

Almost surely, 2^21519755 is an apocalyptic number.

21519755 is a deficient number, since it is larger than the sum of its proper divisors (5320405).

21519755 is a wasteful number, since it uses less digits than its factorization.

21519755 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1438.

The product of its digits is 15750, while the sum is 35.

The square root of 21519755 is about 4638.9389950720. The cubic root of 21519755 is about 278.1500277103.

The spelling of 21519755 in words is "twenty-one million, five hundred nineteen thousand, seven hundred fifty-five".