21366031 has 4 divisors (see below), whose sum is σ = 21426912. Its totient is φ = 21305152.

The previous prime is 21366017. The next prime is 21366041. The reversal of 21366031 is 13066312.

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 21366031 - 2⁵ = 21365999 is a prime.

It is a super-2 number, since 2×21366031² = 913014561385922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21365993 and 21366011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21366041) 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, 29911 + ... + 30616.

It is an arithmetic number, because the mean of its divisors is an integer number (5356728).

Almost surely, 2^21366031 is an apocalyptic number.

21366031 is a deficient number, since it is larger than the sum of its proper divisors (60881).

21366031 is an equidigital number, since it uses as much as digits as its factorization.

21366031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60880.

The product of its (nonzero) digits is 648, while the sum is 22.

The square root of 21366031 is about 4622.3404245036. The cubic root of 21366031 is about 277.4861330083.

The spelling of 21366031 in words is "twenty-one million, three hundred sixty-six thousand, thirty-one".