21155701 has 24 divisors (see below), whose sum is σ = 26409240. Its totient is φ = 16837632.

The previous prime is 21155681. The next prime is 21155723. The reversal of 21155701 is 10755112.

It can be written as a sum of positive squares in 4 ways, for example, as 4558225 + 16597476 = 2135^2 + 4074^2 .

It is not a de Polignac number, because 21155701 - 2⁵ = 21155669 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155731) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 90681 + ... + 90913.

It is an arithmetic number, because the mean of its divisors is an integer number (1100385).

Almost surely, 2^21155701 is an apocalyptic number.

It is an amenable number.

21155701 is a deficient number, since it is larger than the sum of its proper divisors (5253539).

21155701 is a wasteful number, since it uses less digits than its factorization.

21155701 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 373 (or 366 counting only the distinct ones).

The product of its (nonzero) digits is 350, while the sum is 22.

The square root of 21155701 is about 4599.5326936549. The cubic root of 21155701 is about 276.5725921669.

The spelling of 21155701 in words is "twenty-one million, one hundred fifty-five thousand, seven hundred one".