21393770 has 32 divisors (see below), whose sum is σ = 40186368. Its totient is φ = 8192448.

The previous prime is 21393767. The next prime is 21393773. The reversal of 21393770 is 7739312.

It is an interprime number because it is at equal distance from previous prime (21393767) and next prime (21393773).

It is a Curzon number.

It is a zygodrome in base 9.

It is not an unprimeable number, because it can be changed into a prime (21393773) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24359 + ... + 25221.

It is an arithmetic number, because the mean of its divisors is an integer number (1255824).

Almost surely, 2^21393770 is an apocalyptic number.

21393770 is a deficient number, since it is larger than the sum of its proper divisors (18792598).

21393770 is a wasteful number, since it uses less digits than its factorization.

21393770 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 974.

The product of its (nonzero) digits is 7938, while the sum is 32.

The square root of 21393770 is about 4625.3399875036. The cubic root of 21393770 is about 277.6061655843.

The spelling of 21393770 in words is "twenty-one million, three hundred ninety-three thousand, seven hundred seventy".