21990348 has 18 divisors (see below), whose sum is σ = 55586804. Its totient is φ = 7330104.

The previous prime is 21990347. The next prime is 21990349. The reversal of 21990348 is 84309912.

It is an interprime number because it is at equal distance from previous prime (21990347) and next prime (21990349).

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-2 number, since 2×21990348² = 967150810322208, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 610843 = 21990348 / (2 + 1 + 9 + 9 + 0 + 3 + 4 + 8).

It is not an unprimeable number, because it can be changed into a prime (21990341) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 305386 + ... + 305457.

Almost surely, 2^21990348 is an apocalyptic number.

It is an amenable number.

21990348 is an abundant number, since it is smaller than the sum of its proper divisors (33596456).

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

21990348 is a wasteful number, since it uses less digits than its factorization.

21990348 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 610853 (or 610848 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 21990348 is about 4689.3867402892. The cubic root of 21990348 is about 280.1629493689.

The spelling of 21990348 in words is "twenty-one million, nine hundred ninety thousand, three hundred forty-eight".