21681470 has 16 divisors (see below), whose sum is σ = 41081040. Its totient is φ = 8216064.

The previous prime is 21681469. The next prime is 21681481. The reversal of 21681470 is 7418612.

It is a super-2 number, since 2×21681470² = 940172282721800, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 56867 + ... + 57246.

It is an arithmetic number, because the mean of its divisors is an integer number (2567565).

Almost surely, 2^21681470 is an apocalyptic number.

21681470 is a deficient number, since it is larger than the sum of its proper divisors (19399570).

21681470 is a wasteful number, since it uses less digits than its factorization.

21681470 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114139.

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 21681470 is about 4656.3365428199. The cubic root of 21681470 is about 278.8450298366.

The spelling of 21681470 in words is "twenty-one million, six hundred eighty-one thousand, four hundred seventy".