21291004 has 24 divisors (see below), whose sum is σ = 45087840. Its totient is φ = 8587776.

The previous prime is 21290999. The next prime is 21291007. The reversal of 21291004 is 40019212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21291007) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21889 + ... + 22840.

It is an arithmetic number, because the mean of its divisors is an integer number (1878660).

Almost surely, 2^21291004 is an apocalyptic number.

It is an amenable number.

21291004 is an abundant number, since it is smaller than the sum of its proper divisors (23796836).

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

21291004 is a wasteful number, since it uses less digits than its factorization.

21291004 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44757 (or 44755 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 21291004 is about 4614.2175934821. The cubic root of 21291004 is about 277.1609537804.

The spelling of 21291004 in words is "twenty-one million, two hundred ninety-one thousand, four".