21970787 has 4 divisors (see below), whose sum is σ = 22037496. Its totient is φ = 21904080.

The previous prime is 21970771. The next prime is 21970811. The reversal of 21970787 is 78707912.

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

It is a cyclic number.

It is not a de Polignac number, because 21970787 - 2⁴ = 21970771 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21970717) 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, 32858 + ... + 33519.

It is an arithmetic number, because the mean of its divisors is an integer number (5509374).

Almost surely, 2^21970787 is an apocalyptic number.

21970787 is a deficient number, since it is larger than the sum of its proper divisors (66709).

21970787 is an equidigital number, since it uses as much as digits as its factorization.

21970787 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66708.

The product of its (nonzero) digits is 49392, while the sum is 41.

The square root of 21970787 is about 4687.3006090926. The cubic root of 21970787 is about 280.0798539248.

The spelling of 21970787 in words is "twenty-one million, nine hundred seventy thousand, seven hundred eighty-seven".