21690501 has 8 divisors (see below), whose sum is σ = 33052224. Its totient is φ = 12394560.

The previous prime is 21690499. The next prime is 21690523. The reversal of 21690501 is 10509612.

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

It is not a de Polignac number, because 21690501 - 2¹ = 21690499 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21692501) 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, 516420 + ... + 516461.

It is an arithmetic number, because the mean of its divisors is an integer number (4131528).

Almost surely, 2^21690501 is an apocalyptic number.

21690501 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21690501 is a deficient number, since it is larger than the sum of its proper divisors (11361723).

21690501 is a wasteful number, since it uses less digits than its factorization.

21690501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1032891.

The product of its (nonzero) digits is 540, while the sum is 24.

The square root of 21690501 is about 4657.3061956457. The cubic root of 21690501 is about 278.8837403100.

The spelling of 21690501 in words is "twenty-one million, six hundred ninety thousand, five hundred one".