21353764 has 6 divisors (see below), whose sum is σ = 37369094. Its totient is φ = 10676880.

The previous prime is 21353737. The next prime is 21353767. The reversal of 21353764 is 46735312.

It can be written as a sum of positive squares in only one way, i.e., 13468900 + 7884864 = 3670^2 + 2808^2 .

It is not an unprimeable number, because it can be changed into a prime (21353767) 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 as a sum of consecutive naturals, namely, 2669217 + ... + 2669224.

Almost surely, 2^21353764 is an apocalyptic number.

It is an amenable number.

21353764 is a deficient number, since it is larger than the sum of its proper divisors (16015330).

21353764 is a wasteful number, since it uses less digits than its factorization.

21353764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5338445 (or 5338443 counting only the distinct ones).

The product of its digits is 15120, while the sum is 31.

The square root of 21353764 is about 4621.0133087885. The cubic root of 21353764 is about 277.4330179486.

The spelling of 21353764 in words is "twenty-one million, three hundred fifty-three thousand, seven hundred sixty-four".