21510701 has 4 divisors (see below), whose sum is σ = 21551004. Its totient is φ = 21470400.

The previous prime is 21510659. The next prime is 21510703. The reversal of 21510701 is 10701512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4708900 + 16801801 = 2170^2 + 4099^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21510701 is a prime.

It is a super-2 number, since 2×21510701² = 925420515022802, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21510701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21510703) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19340 + ... + 20421.

It is an arithmetic number, because the mean of its divisors is an integer number (5387751).

Almost surely, 2^21510701 is an apocalyptic number.

It is an amenable number.

21510701 is a deficient number, since it is larger than the sum of its proper divisors (40303).

21510701 is an equidigital number, since it uses as much as digits as its factorization.

21510701 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40302.

The product of its (nonzero) digits is 70, while the sum is 17.

The square root of 21510701 is about 4637.9630227073. The cubic root of 21510701 is about 278.1110135794. Note that the first 3 decimals are identical.

The spelling of 21510701 in words is "twenty-one million, five hundred ten thousand, seven hundred one".