21912506 has 24 divisors (see below), whose sum is σ = 41713056. Its totient is φ = 8536920.

The previous prime is 21912503. The next prime is 21912509. The reversal of 21912506 is 60521912.

It is an interprime number because it is at equal distance from previous prime (21912503) and next prime (21912509).

It is not an unprimeable number, because it can be changed into a prime (21912503) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9086 + ... + 11241.

It is an arithmetic number, because the mean of its divisors is an integer number (1738044).

Almost surely, 2^21912506 is an apocalyptic number.

21912506 is a deficient number, since it is larger than the sum of its proper divisors (19800550).

21912506 is a wasteful number, since it uses less digits than its factorization.

21912506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20354 (or 20347 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 21912506 is about 4681.0795763371. The cubic root of 21912506 is about 279.8319825325.

The spelling of 21912506 in words is "twenty-one million, nine hundred twelve thousand, five hundred six".