21487690 has 32 divisors (see below), whose sum is σ = 45287424. Its totient is φ = 7186560.

The previous prime is 21487673. The next prime is 21487693. The reversal of 21487690 is 9678412.

It is a super-2 number, since 2×21487690² = 923441643072200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21487693) 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 in 15 ways as a sum of consecutive naturals, for example, 874 + ... + 6613.

It is an arithmetic number, because the mean of its divisors is an integer number (1415232).

Almost surely, 2^21487690 is an apocalyptic number.

21487690 is an abundant number, since it is smaller than the sum of its proper divisors (23799734).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21487690 is a wasteful number, since it uses less digits than its factorization.

21487690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7542.

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 21487690 is about 4635.4816362488. The cubic root of 21487690 is about 278.0118087560.

The spelling of 21487690 in words is "twenty-one million, four hundred eighty-seven thousand, six hundred ninety".