21421490 has 8 divisors (see below), whose sum is σ = 38558700. Its totient is φ = 8568592.

The previous prime is 21421489. The next prime is 21421537. The reversal of 21421490 is 9412412.

It can be written as a sum of positive squares in 2 ways, for example, as 20857489 + 564001 = 4567^2 + 751^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1071065 + ... + 1071084.

Almost surely, 2^21421490 is an apocalyptic number.

21421490 is a deficient number, since it is larger than the sum of its proper divisors (17137210).

21421490 is a wasteful number, since it uses less digits than its factorization.

21421490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2142156.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 21421490 is about 4628.3355539546. The cubic root of 21421490 is about 277.7260123390.

The spelling of 21421490 in words is "twenty-one million, four hundred twenty-one thousand, four hundred ninety".